USPS package barcodes, service type codes and mailing terms, each cited to its USPS source.
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Read a package barcode or tracking number (IMpb): its layout, each field's digits and meaning, whether the check digit holds, and the service type code's row in the USPS list, each with the passage that says so.
Pick your client. Values in capitals, like YOUR_TOKEN, are yours to fill in.
claude mcp add --transport http postalref https://postalref.com/mcp
Read a package barcode or tracking number (IMpb): its layout, each field's digits and meaning, whether the check digit holds, and the service type code's row in the USPS list, each with the passage that says so.
| Argument | Type | Description |
|---|---|---|
| barcode* | string |
{
"type": "object",
"required": [
"barcode"
],
"properties": {
"barcode": {
"type": "string",
"maxLength": 80
}
},
"additionalProperties": false
}What USPS means by a name or abbreviation: each registry entry it names, with the USPS words that define it and the page they're on, its other names, postalref's own explanation where it has one, and postalref's page about it.
| Argument | Type | Description |
|---|---|---|
| name* | string | A name or abbreviation USPS uses: mailer id, MID, CRID, banner text. |
| limit | integer | At most this many entries; 5 when absent. |
{
"type": "object",
"required": [
"name"
],
"properties": {
"name": {
"type": "string",
"maxLength": 120,
"description": "A name or abbreviation USPS uses: mailer id, MID, CRID, banner text."
},
"limit": {
"type": "integer",
"maximum": 20,
"minimum": 1,
"description": "At most this many entries; 5 when absent."
}
},
"additionalProperties": false
}What changed in a code table or document between two editions: each code added, removed or changed and each changed section, rated editorial, additive or breaking, with who rated it.
| Argument | Type | Description |
|---|---|---|
| to | string | The newer edition's date. The newest when absent. |
| code | string | One code of the table. |
| from | string | The older edition's date. The edition before `to` when absent. |
| limit | integer | At most this many changes; 50 when absent. |
| subject* | string | A code table, such as stc, ptr or extra-services, or a document, such as pub-199 or impb-spec. |
| severity | string | Only changes rated this. |
{
"type": "object",
"required": [
"subject"
],
"properties": {
"to": {
"type": "string",
"description": "The newer edition's date. The newest when absent."
},
"code": {
"type": "string",
"maxLength": 40,
"description": "One code of the table."
},
"from": {
"type": "string",
"description": "The older edition's date. The edition before `to` when absent."
},
"limit": {
"type": "integer",
"maximum": 200,
"minimum": 1,
"description": "At most this many changes; 50 when absent."
},
"subject": {
"type": "string",
"description": "A code table, such as stc, ptr or extra-services, or a document, such as pub-199 or impb-spec."
},
"severity": {
"enum": [
"editorial",
"additive",
"breaking"
],
"type": "string",
"description": "Only changes rated this."
}
},
"additionalProperties": false
}Look up a USPS code: its row as USPS prints it in the newest edition that lists it, the codes its cells name, the editions that list it and its history, each row with its passage id.
| Argument | Type | Description |
|---|---|---|
| code* | string | A code as USPS prints it: 055, 920, PM, 01. |
| table | string | One table to look in: stc, extra-services, mail-classes, ptr, ptr2 or stid. Every table when absent. |
{
"type": "object",
"required": [
"code"
],
"properties": {
"code": {
"type": "string",
"maxLength": 40,
"description": "A code as USPS prints it: 055, 920, PM, 01."
},
"table": {
"type": "string",
"description": "One table to look in: stc, extra-services, mail-classes, ptr, ptr2 or stid. Every table when absent."
}
},
"additionalProperties": false
}Read a revision of a modeled USPS document page by page, as extracted, to quote it: a quote cites the revision's sha256, the PDF page and the words exactly.
| Argument | Type | Description |
|---|---|---|
| find | string | Words to find, as one phrase, or when no page has the phrase, each word anywhere on a page. Without `page`, the text read is the first pages that have them. |
| page | integer | The first PDF page, or sheet, to read, counting from 1. Absent with `find`: the pages that have the words. |
| pages | integer | How many to read, up to 5; 1 when absent. |
| document* | string | A modeled document: pub-199, impb-spec, stc-list, ptr-events, ptr2-events, stid-table, imb-spec or parcel-labeling-guide. |
| revision | string | A revision's sha256, or its slug, such as 2026-07-02. The newest when absent. |
{
"type": "object",
"required": [
"document"
],
"properties": {
"find": {
"type": "string",
"maxLength": 200,
"description": "Words to find, as one phrase, or when no page has the phrase, each word anywhere on a page. Without `page`, the text read is the first pages that have them."
},
"page": {
"type": "integer",
"maximum": 9007199254740991,
"minimum": 1,
"description": "The first PDF page, or sheet, to read, counting from 1. Absent with `find`: the pages that have the words."
},
"pages": {
"type": "integer",
"maximum": 5,
"minimum": 1,
"description": "How many to read, up to 5; 1 when absent."
},
"document": {
"type": "string",
"description": "A modeled document: pub-199, impb-spec, stc-list, ptr-events, ptr2-events, stid-table, imb-spec or parcel-labeling-guide."
},
"revision": {
"type": "string",
"maxLength": 64,
"description": "A revision's sha256, or its slug, such as 2026-07-02. The newest when absent."
}
},
"additionalProperties": false
}Search the codes, terms, specs and documents postalref models, exact names and codes first. A query of 20 or more digits comes back as one to decode.
| Argument | Type | Description |
|---|---|---|
| limit | integer | At most this many hits; 10 when absent. |
| query* | string | A code, a term or words from a code's row: 055, mailer id, ground advantage. |
{
"type": "object",
"required": [
"query"
],
"properties": {
"limit": {
"type": "integer",
"maximum": 50,
"minimum": 1,
"description": "At most this many hits; 10 when absent."
},
"query": {
"type": "string",
"maxLength": 120,
"description": "A code, a term or words from a code's row: 055, mailer id, ground advantage."
}
},
"additionalProperties": false
}Search every document on PostalPro by title and file name, with its page and newest file. postalref models a few of them; those carry a slug for read_source.
| Argument | Type | Description |
|---|---|---|
| limit | integer | At most this many; 10 when absent. |
| query* | string | Words from a document's title or file name. |
| topic | string | Only documents a model put under this topic. |
{
"type": "object",
"required": [
"query"
],
"properties": {
"limit": {
"type": "integer",
"maximum": 50,
"minimum": 1,
"description": "At most this many; 10 when absent."
},
"query": {
"type": "string",
"maxLength": 120,
"description": "Words from a document's title or file name."
},
"topic": {
"enum": [
"mailing",
"shipping",
"address-quality",
"visibility",
"promotions",
"operations",
"accounts",
"industry",
"international",
"other"
],
"type": "string",
"description": "Only documents a model put under this topic."
}
},
"additionalProperties": false
}We read every tool's name, description and inputs the way the model will, looking for instructions hidden from you. A clean result means no warning signs, not a guarantee. Scanned Oct 31, 2026.