Search and trace US federal rules across the Federal Register, eCFR, and Regulations.gov.
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Explore the codified Code of Federal Regulations via eCFR in two modes. "structure" lists all 50 titles; with a title, that title's top-level divisions (its chapters, or subtitles); and with a title and part, every section and appendix in the part, flattened and paged, each naming the subpart and subject group it sits under — the way to enumerate a part's sections without reading its text. "search" runs a full-text query across the codified CFR and returns matching sections with their hierarchy path and a snippet, one result per section, paged. Both modes accept title and part to narrow the scope. Both feed regulations_get_cfr_section. Every search result reports which corpus answered it — the synced local mirror or the live eCFR index — and what that corpus covers, in `source` and `sourceScope`.
"structure": list titles, a title's top-level divisions, or a part's sections and appendices, to find a cite. "search": full-text search the codified CFR for sections matching a phrase.
Point-in-time date, ISO 8601 (YYYY-MM-DD). Defaults to current. Structure mode uses it for the historical hierarchy, and rejects a date past the title's up-to-date date. Search mode matches only the section text in effect on that day, so a past date searches the CFR as it read then; eCFR indexes 2017-01-03 onward and rejects a date past its current index date.
1-based page of search results, or of a part's listing in structure mode (default 1); ignored by a structure listing above a part, which comes back whole. A truncation notice names the next page. Live eCFR search pages through its first 10,000 hits only, so a page starting past them is refused — narrow the query instead of paging deeper.
CFR part within the title, in both modes — structure mode lists every section and appendix in the part, flattened and paged by page/per_page; search mode restricts matches to text inside that part. Requires title; a part on its own is rejected. Parts can be alphanumeric ("1203a", "16A") and are matched exactly once a leading "Part" or "Pt." is dropped, so pass the identifier as eCFR writes it — "58" ("Part 58" also reads as 58), not "058".
Full-text search phrase (search mode, required in that mode). Ignored in structure mode.
CFR title number (1–50). Structure mode: omit to list all 50 titles; provide it alone to list the title's top-level divisions (chapters, or subtitles) — not the parts beneath them — or with part to list that part. Search mode: optional filter restricting matches to that title — e.g. 40 for environmental rules, 21 for food and drugs.
Rows per page — search results, or nodes of a part's listing in structure mode (1–50, default 20).
Explore the codified Code of Federal Regulations via eCFR in two modes. "structure" lists all 50 titles; with a title, that title's top-level divisions (its chapters, or subtitles); and with a title and part, every section and appendix in the part, flattened and paged, each naming the subpart and subject group it sits under — the way to enumerate a part's sections without reading its text. "search" runs a full-text query across the codified CFR and returns matching sections with their hierarchy path and a snippet, one result per section, paged. Both modes accept title and part to narrow the scope. Both feed regulations_get_cfr_section. Every search result reports which corpus answered it — the synced local mirror or the live eCFR index — and what that corpus covers, in `source` and `sourceScope`.
| Argument | Type | Description |
|---|---|---|
| date | any | Point-in-time date, ISO 8601 (YYYY-MM-DD). Defaults to current. Structure mode uses it for the historical hierarchy, and rejects a date past the title's up-to-date date. Search mode matches only the section text in effect on that day, so a past date searches the CFR as it read then; eCFR indexes 2017-01-03 onward and rejects a date past its current index date. |
| mode* | string | "structure": list titles, a title's top-level divisions, or a part's sections and appendices, to find a cite. "search": full-text search the codified CFR for sections matching a phrase. |
| page | integer | 1-based page of search results, or of a part's listing in structure mode (default 1); ignored by a structure listing above a part, which comes back whole. A truncation notice names the next page. Live eCFR search pages through its first 10,000 hits only, so a page starting past them is refused — narrow the query instead of paging deeper. |
| part | string | CFR part within the title, in both modes — structure mode lists every section and appendix in the part, flattened and paged by page/per_page; search mode restricts matches to text inside that part. Requires title; a part on its own is rejected. Parts can be alphanumeric ("1203a", "16A") and are matched exactly once a leading "Part" or "Pt." is dropped, so pass the identifier as eCFR writes it — "58" ("Part 58" also reads as 58), not "058". |
| query | any | Full-text search phrase (search mode, required in that mode). Ignored in structure mode. |
| title | integer | CFR title number (1–50). Structure mode: omit to list all 50 titles; provide it alone to list the title's top-level divisions (chapters, or subtitles) — not the parts beneath them — or with part to list that part. Search mode: optional filter restricting matches to that title — e.g. 40 for environmental rules, 21 for food and drugs. |
| per_page | integer | Rows per page — search results, or nodes of a part's listing in structure mode (1–50, default 20). |
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"mode"
],
"properties": {
"date": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "Point-in-time date, ISO 8601 (YYYY-MM-DD). Defaults to current. Structure mode uses it for the historical hierarchy, and rejects a date past the title's up-to-date date. Search mode matches only the section text in effect on that day, so a past date searches the CFR as it read then; eCFR indexes 2017-01-03 onward and rejects a date past its current index date."
},
"mode": {
"enum": [
"structure",
"search"
],
"type": "string",
"description": "\"structure\": list titles, a title's top-level divisions, or a part's sections and appendices, to find a cite. \"search\": full-text search the codified CFR for sections matching a phrase."
},
"page": {
"type": "integer",
"default": 1,
"maximum": 9007199254740991,
"minimum": 1,
"description": "1-based page of search results, or of a part's listing in structure mode (default 1); ignored by a structure listing above a part, which comes back whole. A truncation notice names the next page. Live eCFR search pages through its first 10,000 hits only, so a page starting past them is refused — narrow the query instead of paging deeper."
},
"part": {
"type": "string",
"description": "CFR part within the title, in both modes — structure mode lists every section and appendix in the part, flattened and paged by page/per_page; search mode restricts matches to text inside that part. Requires title; a part on its own is rejected. Parts can be alphanumeric (\"1203a\", \"16A\") and are matched exactly once a leading \"Part\" or \"Pt.\" is dropped, so pass the identifier as eCFR writes it — \"58\" (\"Part 58\" also reads as 58), not \"058\"."
},
"query": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"minLength": 2,
"description": "Search phrase, at least 2 characters."
}
],
"description": "Full-text search phrase (search mode, required in that mode). Ignored in structure mode."
},
"title": {
"type": "integer",
"maximum": 50,
"minimum": 1,
"description": "CFR title number (1–50). Structure mode: omit to list all 50 titles; provide it alone to list the title's top-level divisions (chapters, or subtitles) — not the parts beneath them — or with part to list that part. Search mode: optional filter restricting matches to that title — e.g. 40 for environmental rules, 21 for food and drugs."
},
"per_page": {
"type": "integer",
"default": 20,
"maximum": 50,
"minimum": 1,
"description": "Rows per page — search results, or nodes of a part's listing in structure mode (1–50, default 20)."
}
},
"additionalProperties": false
}Fetch public comments on a Federal Register document or a Regulations.gov docket — the unique corpus of what citizens and organizations actually submitted. Provide exactly one targeting parameter: docket_id (all comments in a docket, broadest), document_object_id (comments on one document, by its object ID or document ID), fr_document_number (convenience — resolves the FR number to the Regulations.gov document carrying it), or comment_id (one comment's full detail and attachments). A list narrows by comment text with search_term (each hit then carries the matching passages) and by posted date with posted_after/posted_before. The list endpoint returns no body text or attachment info — call with comment_id to read a comment's body. When a comment's real content is a PDF/DOCX attachment, the body is a stub and attachmentOnly is true; the attachment download URLs are returned. Requires REGULATIONS_GOV_API_KEY (free at https://api.data.gov/signup/).
| Argument | Type | Description |
|---|---|---|
| page | integer | Page number (1–40, default 1). Regulations.gov serves 40 pages, so a list reaches 40 × per_page comments (10,000 at per_page 250); totalPages and nextPage in the response say how far this one goes. To reach past that, take the set one posted_after/posted_before window at a time. |
| per_page | integer | Comments per page (5–250, default 25). Regulations.gov requires a minimum page size of 5. |
| docket_id | string | Fetch all comments in a docket by Regulations.gov docket ID (e.g. "EPA-HQ-OAR-2025-0194") — regulationsGovDocketId on a regulations_search_rules or regulations_list_open_comments row, or docketId from regulations_get_document, not an entry of the printed docketIds. Broadest scope. Exactly one of docket_id / document_object_id / fr_document_number / comment_id is required — supplying two is rejected, not resolved by precedence. |
Read the codified text at a CFR location via eCFR — current or as of a past date. Answers "what does 40 CFR 50.1 say today?" and "...as of 2019-01-01?". Three locations: title + part + section for one section; title + part alone for the whole part, with its Authority and Source notes, an index of its sections, and the names of its appendices; title + appendix for one appendix, passing the identifier exactly as regulations_browse_cfr emits it. A section can be written as people cite it — "61", "§ 141.61", "141.61(c)", or the full cite "40 CFR 141.61" in part 141 all read 40 CFR 141.61 — and a part as "Part 141"; the response names the identifier it read. Text comes back as a window of up to 64,000 characters (max_chars raises it to 200,000) with the total length and, when text remains, the offset to resume from; whole parts run to millions of characters, so page with offset or read a single section. eCFR retains historical versions from 2017 through the title's up-to-date date; a date outside that window is rejected with the window named. Current single-section reads are served from a synced local mirror when it holds the title's latest eCFR issue; the source is reported.
| Argument | Type | Description |
|---|---|---|
| date | any | Point-in-time date, ISO 8601 (YYYY-MM-DD). Default current. eCFR serves 2017-01-01 through the title's up-to-date date, usually a few days behind today; a date outside that window is rejected, naming the window. |
| part | string | CFR part within the title (e.g. "50"). Parts can be alphanumeric; a leading "Part" or "Pt." is dropped ("Part 141" reads part 141). Required unless appendix is given, where it is optional but recommended: an appendix identifier is unique within a part, not within a title, so without a part eCFR picks one of the matches. Obtain from regulations_browse_cfr or a Federal Register document's cfrReferences. |
Pull a rulemaking docket from Regulations.gov by docket ID (e.g. "EPA-HQ-OAR-2025-0194") — the docket's metadata (title, agency, RIN, abstract) and the documents filed in it (NPRM, final rule, supporting materials). The docket is the folder holding a rule's whole paper trail; each returned document's objectId feeds regulations_find_comments. A docket often contains hundreds of supporting materials — filter document_types to "Proposed Rule"/"Rule" to find the rule documents themselves. Requires REGULATIONS_GOV_API_KEY (free at https://api.data.gov/signup/); the Federal Register and eCFR tools work without it.
| Argument | Type | Description |
|---|---|---|
| page | integer | Page number (1–40, default 1). Regulations.gov serves 40 pages, so a docket listing reaches 40 × per_page documents (10,000 at per_page 250); totalPages and nextPage in the response say how far this one goes. Beyond that, narrow with document_types. |
| per_page | integer | Documents per page (5–250, default 25). Regulations.gov requires a minimum page size of 5. |
| docket_id* | string | Regulations.gov docket ID (e.g. "EPA-HQ-OAR-2025-0194"). Obtain from regulationsGovDocketId on a regulations_search_rules or regulations_list_open_comments row, or docketId from regulations_get_document. The printed docketIds on those tools are not always Regulations.gov IDs ("REG-101355-26" is the IRS's own number for docket IRS-2026-0925). |
| document_types | array | Filter the docket's documents to these types. Omit for all. A docket often contains hundreds of "Supporting & Related Material" items — filter to "Proposed Rule"/"Rule" to find the rule documents. |
Fetch one Federal Register document by its FR document number — full metadata (title, type, agencies, abstract, action, effective/comment dates, RINs) plus the cross-source handles that make this a workflow server. The output carries the Regulations.gov docket ID (chain into regulations_get_docket or regulations_find_comments), the docket numbers the Federal Register prints (chain back into regulations_search_rules as docket_id), the comment count and comment URL, and the affected CFR parts (chain into regulations_get_cfr_section). Set include_full_text only when the rule body itself is needed: it returns the plain-text body as a window of up to 64,000 characters (max_chars raises it to 200,000), with the body's total length and, when text remains, the offset to resume from. Short documents return whole; major final rules run past a million characters, so page through with offset rather than reading them in one call.
| Argument | Type | Description |
|---|---|---|
| offset | integer | Character offset into the plain-text body where the window starts (default 0). Pass the fullTextNextOffset from the previous call to read on. Implies include_full_text. |
| max_chars | integer | Most body characters to return in this window (1–200,000, default 64,000). Implies include_full_text. |
| document_number* | string | Federal Register document number, as regulations_search_rules returns it in documentNumber: "2024-07773" from 2010 on, older and correction numbers like "98-1572", "E9-25990", or "C1-2009-30484". |
| include_full_text | boolean | When true, inline one window of the document body as plain text (see offset and max_chars). Omitted, the body URLs alone come back unless offset or max_chars is passed; fetch full text only when you need to read the rule itself, not just its metadata and cross-links. |
List Federal Register documents currently open for public comment, sorted by closing date (soonest first) across the whole open window, filterable by document type, agency slug, and topic. "What can I still weigh in on?" Covers proposed rules and the final rules that take comment (direct final and interim final rules) by default; add NOTICE for the much larger set of notices with comment periods. Runs on the Federal Register's open-comment window and needs no key: each row carries its Regulations.gov docket and document IDs, comment count, and comment URL from the Federal Register document's embedded Regulations.gov info. Open one row with regulations_get_document for the full document, or pull the comments with regulations_find_comments (which, like regulations_get_docket, needs REGULATIONS_GOV_API_KEY).
| Argument | Type | Description |
|---|---|---|
| page | integer | Page number, default 1. Pages run over the whole open window in closing-date order; totalPages and nextPage in the response say how far it goes. |
| type | array | Document types to include: PRORULE (proposed rules), RULE (final rules that request comment, including direct final and interim final rules), NOTICE (information-collection and other notices with comment periods — a much larger set). Default, and when empty: ["PRORULE", "RULE"]. |
| query | string | Full-text filter across open documents. Omit to list every document currently open for comment. |
| agencies | array | Filter to one or more agencies by Federal Register agency slug (e.g. "environmental-protection-agency") — lowercase kebab-case, not a name or acronym. Every row lists its agencies with their slugs; read agencies[].slug off a row here or in regulations_search_rules. One unrecognized slug fails the whole request. |
Search the Federal Register — the daily journal of US proposed rules, final rules, notices, and presidential documents (1994–present) — filtering by full-text query, document type, agency slug, publication date range, affected CFR title and part, printed docket number, and RIN, all combined. A page cite from a CFR source note ("89 FR 49102", with its date) resolves to the documents printed on that page. The primary discovery entry point: results carry the document number (open with regulations_get_document), its citation and page range, each issuing agency with its filterable slug, printed docket numbers, Regulations.gov docket and document IDs, comment count and comment URL, whether the comment period is open, RINs, and affected CFR parts that chain into the comment and codified-text tools. A query ranks by relevance unless order says otherwise; filter-only browsing lists newest first. The Federal Register caps navigation at 50 pages and the match count at 10,000; when a result set is larger, narrow with published_after/published_before rather than paging deeper.
| Argument | Type | Description |
|---|---|---|
| rin | string | Only documents carrying this Regulation Identifier Number — a regulationIdNumbers entry such as "2040-AG18", which follows one rulemaking from proposal to final rule. Pass the complete RIN: a fragment ("2040") matches every RIN that contains it. |
| page | integer | Page number (1–50, default 1). The Federal Register serves 50 pages, so a query reaches 50 × per_page matches (5,000 at per_page 100); totalPages and nextPage in the response say how far this one goes. To reach past that, narrow with published_after/published_before rather than paging deeper. |
| type | array | Document types to include. PRORULE=Proposed Rule, RULE=Final Rule, NOTICE=Notice, PRESDOCU=Presidential Document. Omit for all types. |
| comment_id | string | Fetch one comment's full detail and attachments by its Regulations.gov comment ID (e.g. "EPA-HQ-OAR-2025-0194-31102"). Use to read a single comment's body after finding it in a list. Mutually exclusive with the other three targeting parameters — pass it alone, not alongside the docket it came from — and takes none of the list filters. |
| search_term | string | List mode: keep only comments whose text matches, as Regulations.gov full-text search reads it — stemmed, so "flaring" also matches "flare" and "flares". Each hit then carries highlightedContent, the passages that matched. |
| posted_after | any | List mode: earliest posted date, inclusive, ISO 8601 (YYYY-MM-DD), a real calendar day. Pair with posted_before to take a high-volume set one window at a time. |
| posted_before | any | List mode: latest posted date, inclusive, ISO 8601 (YYYY-MM-DD), a real calendar day. The same date as posted_after selects that one day. |
| document_object_id | string | Fetch comments on one specific Regulations.gov document, by either handle: its object ID, 16 hex characters (e.g. "0900006485883ec6", the objectId in regulations_get_docket's documents), or its document ID (e.g. "EPA-HQ-OW-2022-0114-0027", the regulationsGovDocumentId from regulations_get_document). Comments usually attach to the docket's primary (proposed-rule) document. Mutually exclusive with the other three targeting parameters. |
| fr_document_number | any | Convenience: fetch comments on the Regulations.gov document carrying a Federal Register number (e.g. "2023-05471"; older numbers like "E9-25990" too). A Regulations.gov document ID ("EPA-HQ-OW-2022-0114-0027") is not an FR number; pass it as document_object_id. Saves a get_document → get_docket hop. A document that is not on Regulations.gov — a presidential document, for one — answers not_found. Mutually exclusive with the other three targeting parameters. |
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"page": {
"type": "integer",
"default": 1,
"maximum": 40,
"minimum": 1,
"description": "Page number (1–40, default 1). Regulations.gov serves 40 pages, so a list reaches 40 × per_page comments (10,000 at per_page 250); totalPages and nextPage in the response say how far this one goes. To reach past that, take the set one posted_after/posted_before window at a time."
},
"per_page": {
"type": "integer",
"default": 25,
"maximum": 250,
"minimum": 5,
"description": "Comments per page (5–250, default 25). Regulations.gov requires a minimum page size of 5."
},
"docket_id": {
"type": "string",
"description": "Fetch all comments in a docket by Regulations.gov docket ID (e.g. \"EPA-HQ-OAR-2025-0194\") — regulationsGovDocketId on a regulations_search_rules or regulations_list_open_comments row, or docketId from regulations_get_document, not an entry of the printed docketIds. Broadest scope. Exactly one of docket_id / document_object_id / fr_document_number / comment_id is required — supplying two is rejected, not resolved by precedence."
},
"comment_id": {
"type": "string",
"description": "Fetch one comment's full detail and attachments by its Regulations.gov comment ID (e.g. \"EPA-HQ-OAR-2025-0194-31102\"). Use to read a single comment's body after finding it in a list. Mutually exclusive with the other three targeting parameters — pass it alone, not alongside the docket it came from — and takes none of the list filters."
},
"search_term": {
"type": "string",
"description": "List mode: keep only comments whose text matches, as Regulations.gov full-text search reads it — stemmed, so \"flaring\" also matches \"flare\" and \"flares\". Each hit then carries highlightedContent, the passages that matched."
},
"posted_after": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "List mode: earliest posted date, inclusive, ISO 8601 (YYYY-MM-DD), a real calendar day. Pair with posted_before to take a high-volume set one window at a time."
},
"posted_before": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "List mode: latest posted date, inclusive, ISO 8601 (YYYY-MM-DD), a real calendar day. The same date as posted_after selects that one day."
},
"document_object_id": {
"type": "string",
"description": "Fetch comments on one specific Regulations.gov document, by either handle: its object ID, 16 hex characters (e.g. \"0900006485883ec6\", the objectId in regulations_get_docket's documents), or its document ID (e.g. \"EPA-HQ-OW-2022-0114-0027\", the regulationsGovDocumentId from regulations_get_document). Comments usually attach to the docket's primary (proposed-rule) document. Mutually exclusive with the other three targeting parameters."
},
"fr_document_number": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^[A-Za-z]?[0-9]{1,4}-[0-9]{1,6}(-[0-9]{1,6})?$",
"description": "Federal Register document number (e.g. \"2023-05471\", \"E9-25990\")."
}
],
"description": "Convenience: fetch comments on the Regulations.gov document carrying a Federal Register number (e.g. \"2023-05471\"; older numbers like \"E9-25990\" too). A Regulations.gov document ID (\"EPA-HQ-OW-2022-0114-0027\") is not an FR number; pass it as document_object_id. Saves a get_document → get_docket hop. A document that is not on Regulations.gov — a presidential document, for one — answers not_found. Mutually exclusive with the other three targeting parameters."
}
},
"additionalProperties": false
}| title* |
| integer |
| CFR title number (1–50). E.g. 40 for "Protection of Environment". |
| offset | integer | Character offset into the text where the window starts (default 0). Pass bodyTextNextOffset from the previous call to read on, or a sections[].offset from a whole-part read to jump to that section. |
| section | any | Section within the part, normally written part.section as eCFR identifies it ("141.61"). Also accepted: the number alone ("61" in part 141), a leading "§" or "Sec.", a paragraph cite ("141.61(c)"), which reads the whole section, and the full cite this tool returns as cfrCite ("40 CFR 141.61", "14 CFR 241 § 25"), whose title has to match title. Identifiers eCFR writes differently are read as given — 14 CFR 241 numbers its sections "25" and "1-1". Omit to fetch the entire part. Cannot be combined with appendix. |
| appendix | any | Appendix identifier, verbatim as eCFR writes it — the `appendix` field or the leading phrase of the `cfrCite` on a regulations_browse_cfr appendix node or search hit. It is free-form prose, not a letter: "Appendix A-1 to Part 50", "Appendix A to Subpart C of Part 4", "Schedule I to Part 789", "Special Federal Aviation Regulation No. 88". Pass the whole phrase; a short form such as "A-1" matches nothing. Cannot be combined with section. |
| max_chars | integer | Most text characters to return in this window (1–200,000, default 64,000). |
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"title"
],
"properties": {
"date": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "Point-in-time date, ISO 8601 (YYYY-MM-DD). Default current. eCFR serves 2017-01-01 through the title's up-to-date date, usually a few days behind today; a date outside that window is rejected, naming the window."
},
"part": {
"type": "string",
"description": "CFR part within the title (e.g. \"50\"). Parts can be alphanumeric; a leading \"Part\" or \"Pt.\" is dropped (\"Part 141\" reads part 141). Required unless appendix is given, where it is optional but recommended: an appendix identifier is unique within a part, not within a title, so without a part eCFR picks one of the matches. Obtain from regulations_browse_cfr or a Federal Register document's cfrReferences."
},
"title": {
"type": "integer",
"maximum": 50,
"minimum": 1,
"description": "CFR title number (1–50). E.g. 40 for \"Protection of Environment\"."
},
"offset": {
"type": "integer",
"maximum": 9007199254740991,
"minimum": 0,
"description": "Character offset into the text where the window starts (default 0). Pass bodyTextNextOffset from the previous call to read on, or a sections[].offset from a whole-part read to jump to that section."
},
"section": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"description": "Section identifier (e.g. \"50.1\")."
}
],
"description": "Section within the part, normally written part.section as eCFR identifies it (\"141.61\"). Also accepted: the number alone (\"61\" in part 141), a leading \"§\" or \"Sec.\", a paragraph cite (\"141.61(c)\"), which reads the whole section, and the full cite this tool returns as cfrCite (\"40 CFR 141.61\", \"14 CFR 241 § 25\"), whose title has to match title. Identifiers eCFR writes differently are read as given — 14 CFR 241 numbers its sections \"25\" and \"1-1\". Omit to fetch the entire part. Cannot be combined with appendix."
},
"appendix": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"description": "Appendix identifier (e.g. \"Appendix A-1 to Part 50\")."
}
],
"description": "Appendix identifier, verbatim as eCFR writes it — the `appendix` field or the leading phrase of the `cfrCite` on a regulations_browse_cfr appendix node or search hit. It is free-form prose, not a letter: \"Appendix A-1 to Part 50\", \"Appendix A to Subpart C of Part 4\", \"Schedule I to Part 789\", \"Special Federal Aviation Regulation No. 88\". Pass the whole phrase; a short form such as \"A-1\" matches nothing. Cannot be combined with section."
},
"max_chars": {
"type": "integer",
"maximum": 200000,
"minimum": 1,
"description": "Most text characters to return in this window (1–200,000, default 64,000)."
}
},
"additionalProperties": false
}{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"docket_id"
],
"properties": {
"page": {
"type": "integer",
"default": 1,
"maximum": 40,
"minimum": 1,
"description": "Page number (1–40, default 1). Regulations.gov serves 40 pages, so a docket listing reaches 40 × per_page documents (10,000 at per_page 250); totalPages and nextPage in the response say how far this one goes. Beyond that, narrow with document_types."
},
"per_page": {
"type": "integer",
"default": 25,
"maximum": 250,
"minimum": 5,
"description": "Documents per page (5–250, default 25). Regulations.gov requires a minimum page size of 5."
},
"docket_id": {
"type": "string",
"pattern": "^[A-Za-z0-9_-]+$",
"description": "Regulations.gov docket ID (e.g. \"EPA-HQ-OAR-2025-0194\"). Obtain from regulationsGovDocketId on a regulations_search_rules or regulations_list_open_comments row, or docketId from regulations_get_document. The printed docketIds on those tools are not always Regulations.gov IDs (\"REG-101355-26\" is the IRS's own number for docket IRS-2026-0925)."
},
"document_types": {
"type": "array",
"items": {
"enum": [
"Proposed Rule",
"Rule",
"Notice",
"Supporting & Related Material",
"Other"
],
"type": "string"
},
"description": "Filter the docket's documents to these types. Omit for all. A docket often contains hundreds of \"Supporting & Related Material\" items — filter to \"Proposed Rule\"/\"Rule\" to find the rule documents."
}
},
"additionalProperties": false
}{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"document_number"
],
"properties": {
"offset": {
"type": "integer",
"maximum": 9007199254740991,
"minimum": 0,
"description": "Character offset into the plain-text body where the window starts (default 0). Pass the fullTextNextOffset from the previous call to read on. Implies include_full_text."
},
"max_chars": {
"type": "integer",
"maximum": 200000,
"minimum": 1,
"description": "Most body characters to return in this window (1–200,000, default 64,000). Implies include_full_text."
},
"document_number": {
"type": "string",
"pattern": "^[A-Za-z]?[0-9]{1,4}-[0-9]{1,6}(-[0-9]{1,6})?$",
"description": "Federal Register document number, as regulations_search_rules returns it in documentNumber: \"2024-07773\" from 2010 on, older and correction numbers like \"98-1572\", \"E9-25990\", or \"C1-2009-30484\"."
},
"include_full_text": {
"type": "boolean",
"description": "When true, inline one window of the document body as plain text (see offset and max_chars). Omitted, the body URLs alone come back unless offset or max_chars is passed; fetch full text only when you need to read the rule itself, not just its metadata and cross-links."
}
},
"additionalProperties": false
}| per_page | integer | Documents per page (1–100, default 20). |
| closing_before | any | Only documents whose comment period closes on or before this date, ISO 8601 (YYYY-MM-DD), a real calendar day. Use to find deadlines you need to act on soon. |
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"page": {
"type": "integer",
"default": 1,
"maximum": 10000,
"minimum": 1,
"description": "Page number, default 1. Pages run over the whole open window in closing-date order; totalPages and nextPage in the response say how far it goes."
},
"type": {
"type": "array",
"items": {
"enum": [
"PRORULE",
"RULE",
"NOTICE"
],
"type": "string"
},
"description": "Document types to include: PRORULE (proposed rules), RULE (final rules that request comment, including direct final and interim final rules), NOTICE (information-collection and other notices with comment periods — a much larger set). Default, and when empty: [\"PRORULE\", \"RULE\"]."
},
"query": {
"type": "string",
"description": "Full-text filter across open documents. Omit to list every document currently open for comment."
},
"agencies": {
"type": "array",
"items": {
"type": "string"
},
"description": "Filter to one or more agencies by Federal Register agency slug (e.g. \"environmental-protection-agency\") — lowercase kebab-case, not a name or acronym. Every row lists its agencies with their slugs; read agencies[].slug off a row here or in regulations_search_rules. One unrecognized slug fails the whole request."
},
"per_page": {
"type": "integer",
"default": 20,
"maximum": 100,
"minimum": 1,
"description": "Documents per page (1–100, default 20)."
},
"closing_before": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "Only documents whose comment period closes on or before this date, ISO 8601 (YYYY-MM-DD), a real calendar day. Use to find deadlines you need to act on soon."
}
},
"additionalProperties": false
}| order | string | Result order. Defaults to relevance with a query, newest without one. relevance without a query falls back to newest first; oldest lists the earliest publications first. Ignored with citation, whose matches come in page order. |
| query | string | Full-text search across document title and body. Omit to browse by filters alone (e.g. all EPA proposed rules in a date range). |
| agencies | array | Filter to one or more agencies by Federal Register agency slug (e.g. "environmental-protection-agency", "securities-and-exchange-commission") — lowercase kebab-case, not a name or acronym. Every result lists its agencies with their slugs; if unsure, search by query and read agencies[].slug off a result. One unrecognized slug fails the whole request. |
| cfr_part | string | Only documents whose cfrReferences list this part of cfr_title: a part number ("141") or a range ("140-143"), such as the part regulations_get_cfr_section just read; a "Part" or "pt." prefix is dropped. Requires cfr_title. A part with a letter in it ("1203a") cannot be filtered on. Unlike a query of "40 CFR 141", which matches documents that mention the part, this matches the documents whose CFR references list it. |
| citation | any | A Federal Register page cite, "89 FR 49102" (volume FR page) — such as one from the source note that ends a regulations_get_cfr_section bodyText. Returns the documents printed on that page, usually one and sometimes a few sharing it, ordered by start page. Requires citation_date and replaces published_after/published_before. Volume 59 (1994) onward. |
| per_page | integer | Results per page (2–100, default 20). The Federal Register API treats exactly 1 as its default page size instead of returning one result. |
| cfr_title | integer | Only documents whose affected CFR parts (cfrReferences) fall in this title (1–50) — such as the title regulations_get_cfr_section just read. Alone it filters to the title; with cfr_part, to that part. |
| docket_id | string | Only documents carrying this docket number as the Federal Register prints it — a docketIds entry from a result here or from regulations_get_document, with or without a wrapper such as "Docket No.". Lists a docket's Federal Register documents with no REGULATIONS_GOV_API_KEY. A Regulations.gov docket ID matches only where the Federal Register prints it. Pass the complete number: a fragment ("FAA-2026") matches every docket that contains it. |
| citation_date | any | The publication date printed beside the cite in the source note (YYYY-MM-DD) — "89 FR 49102, June 11, 2024" is 2024-06-11. Required with citation; its year is the volume + 1935. |
| published_after | any | Earliest publication date, ISO 8601 (YYYY-MM-DD), a real calendar day. Combine with published_before to window large result sets — the FR caps navigation at 50 pages. |
| published_before | any | Latest publication date, ISO 8601 (YYYY-MM-DD), a real calendar day. |
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"rin": {
"type": "string",
"description": "Only documents carrying this Regulation Identifier Number — a regulationIdNumbers entry such as \"2040-AG18\", which follows one rulemaking from proposal to final rule. Pass the complete RIN: a fragment (\"2040\") matches every RIN that contains it."
},
"page": {
"type": "integer",
"default": 1,
"maximum": 50,
"minimum": 1,
"description": "Page number (1–50, default 1). The Federal Register serves 50 pages, so a query reaches 50 × per_page matches (5,000 at per_page 100); totalPages and nextPage in the response say how far this one goes. To reach past that, narrow with published_after/published_before rather than paging deeper."
},
"type": {
"type": "array",
"items": {
"enum": [
"PRORULE",
"RULE",
"NOTICE",
"PRESDOCU"
],
"type": "string"
},
"description": "Document types to include. PRORULE=Proposed Rule, RULE=Final Rule, NOTICE=Notice, PRESDOCU=Presidential Document. Omit for all types."
},
"order": {
"enum": [
"relevance",
"newest",
"oldest"
],
"type": "string",
"description": "Result order. Defaults to relevance with a query, newest without one. relevance without a query falls back to newest first; oldest lists the earliest publications first. Ignored with citation, whose matches come in page order."
},
"query": {
"type": "string",
"description": "Full-text search across document title and body. Omit to browse by filters alone (e.g. all EPA proposed rules in a date range)."
},
"agencies": {
"type": "array",
"items": {
"type": "string"
},
"description": "Filter to one or more agencies by Federal Register agency slug (e.g. \"environmental-protection-agency\", \"securities-and-exchange-commission\") — lowercase kebab-case, not a name or acronym. Every result lists its agencies with their slugs; if unsure, search by query and read agencies[].slug off a result. One unrecognized slug fails the whole request."
},
"cfr_part": {
"type": "string",
"description": "Only documents whose cfrReferences list this part of cfr_title: a part number (\"141\") or a range (\"140-143\"), such as the part regulations_get_cfr_section just read; a \"Part\" or \"pt.\" prefix is dropped. Requires cfr_title. A part with a letter in it (\"1203a\") cannot be filtered on. Unlike a query of \"40 CFR 141\", which matches documents that mention the part, this matches the documents whose CFR references list it."
},
"citation": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\s*(\\d{1,3})\\s*[Ff]\\.?\\s?[Rr]\\.?\\s*(\\d{1,6})\\s*$",
"description": "Federal Register volume and page, \"89 FR 49102\"."
}
],
"description": "A Federal Register page cite, \"89 FR 49102\" (volume FR page) — such as one from the source note that ends a regulations_get_cfr_section bodyText. Returns the documents printed on that page, usually one and sometimes a few sharing it, ordered by start page. Requires citation_date and replaces published_after/published_before. Volume 59 (1994) onward."
},
"per_page": {
"type": "integer",
"default": 20,
"maximum": 100,
"minimum": 2,
"description": "Results per page (2–100, default 20). The Federal Register API treats exactly 1 as its default page size instead of returning one result."
},
"cfr_title": {
"type": "integer",
"maximum": 50,
"minimum": 1,
"description": "Only documents whose affected CFR parts (cfrReferences) fall in this title (1–50) — such as the title regulations_get_cfr_section just read. Alone it filters to the title; with cfr_part, to that part."
},
"docket_id": {
"type": "string",
"description": "Only documents carrying this docket number as the Federal Register prints it — a docketIds entry from a result here or from regulations_get_document, with or without a wrapper such as \"Docket No.\". Lists a docket's Federal Register documents with no REGULATIONS_GOV_API_KEY. A Regulations.gov docket ID matches only where the Federal Register prints it. Pass the complete number: a fragment (\"FAA-2026\") matches every docket that contains it."
},
"citation_date": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "The publication date printed beside the cite in the source note (YYYY-MM-DD) — \"89 FR 49102, June 11, 2024\" is 2024-06-11. Required with citation; its year is the volume + 1935."
},
"published_after": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "Earliest publication date, ISO 8601 (YYYY-MM-DD), a real calendar day. Combine with published_before to window large result sets — the FR caps navigation at 50 pages."
},
"published_before": {
"anyOf": [
{
"type": "string",
"const": ""
},
{
"type": "string",
"pattern": "^\\d{4}-\\d{2}-\\d{2}$",
"description": "ISO 8601 date (YYYY-MM-DD)."
}
],
"description": "Latest publication date, ISO 8601 (YYYY-MM-DD), a real calendar day."
}
},
"additionalProperties": false
}