Read-only MCP server for the WebAssembly spec: instructions, types, sections, search, proposals.
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Fetch one WebAssembly instruction by mnemonic (`i32.add`) or binary opcode (`0x6a`, multi-byte `0xfd 0x89 0x02`): opcode bytes, category, introducing version, stack type signature, validation/execution anchors + URLs, and `traps` (runtime trap conditions with canonical names; empty + `can_trap:false` when it never traps).
Binary opcode hex, e.g. `0x6a` or `0xfd 0x89 0x02`. Exact.
Instruction mnemonic, e.g. `i32.add`. Case-insensitive, exact.
Fetch one WebAssembly instruction by mnemonic (`i32.add`) or binary opcode (`0x6a`, multi-byte `0xfd 0x89 0x02`): opcode bytes, category, introducing version, stack type signature, validation/execution anchors + URLs, and `traps` (runtime trap conditions with canonical names; empty + `can_trap:false` when it never traps).
| Argument | Type | Description |
|---|---|---|
| opcode | string | Binary opcode hex, e.g. `0x6a` or `0xfd 0x89 0x02`. Exact. |
| mnemonic | string | Instruction mnemonic, e.g. `i32.add`. Case-insensitive, exact. |
{
"type": "object",
"properties": {
"opcode": {
"type": "string",
"description": "Binary opcode hex, e.g. `0x6a` or `0xfd 0x89 0x02`. Exact."
},
"mnemonic": {
"type": "string",
"description": "Instruction mnemonic, e.g. `i32.add`. Case-insensitive, exact."
}
},
"additionalProperties": false
}Enumerate WebAssembly instructions, filterable by `category`, `introduced_in` (1.0|2.0|3.0), mnemonic `prefix`, and `can_trap` (only trapping / only non-trapping). Rows (incl. `can_trap`) sorted by opcode.
| Argument | Type | Description |
|---|---|---|
| prefix | string | Mnemonic prefix, e.g. `i32.`. Case-insensitive. |
| can_trap | boolean | Keep only instructions that can (true) / cannot (false) trap. |
| category | string | Instruction category. |
| introduced_in | string | Introducing version. |
{
"type": "object",
"properties": {
"prefix": {
"type": "string",
"description": "Mnemonic prefix, e.g. `i32.`. Case-insensitive."
},
"can_trap": {
"type": "boolean",
"description": "Keep only instructions that can (true) / cannot (false) trap."
},
"category": {
"enum": [
"control",
"numeric",
"parametric",
"variable",
"table",
"memory",
"ref",
"i31",
"struct",
"array",
"extern",
"vec"
],
"type": "string",
"description": "Instruction category."
},
"introduced_in": {
"enum": [
"1.0",
"2.0",
"3.0"
],
"type": "string",
"description": "Introducing version."
}
},
"additionalProperties": false
}Ranked free-text search across instruction mnemonics, categories, and opcode hex. Returns hits with a `matched_on` field.
| Argument | Type | Description |
|---|---|---|
| limit | integer | Max hits. |
| query* | string | Search text. |
{
"type": "object",
"required": [
"query"
],
"properties": {
"limit": {
"type": "integer",
"maximum": 100,
"minimum": 1,
"description": "Max hits."
},
"query": {
"type": "string",
"description": "Search text."
}
},
"additionalProperties": false
}List WebAssembly proposals + phases. Filter by `status` (phase-0…phase-5, finished, inactive), `phase` (0–5), `champion`, `affects` (core|js-api|web-api), or `contains`.
| Argument | Type | Description |
|---|---|---|
| phase | integer | Numeric phase 0–5. |
| status | string | Lifecycle status. |
| affects | string | Affected spec (finished only). |
| champion | string | Champion substring. |
| contains | string | Name/champion substring. |
{
"type": "object",
"properties": {
"phase": {
"type": "integer",
"maximum": 5,
"minimum": 0,
"description": "Numeric phase 0–5."
},
"status": {
"enum": [
"phase-0",
"phase-1",
"phase-2",
"phase-3",
"phase-4",
"phase-5",
"finished",
"inactive"
],
"type": "string",
"description": "Lifecycle status."
},
"affects": {
"type": "string",
"description": "Affected spec (finished only)."
},
"champion": {
"type": "string",
"description": "Champion substring."
},
"contains": {
"type": "string",
"description": "Name/champion substring."
}
},
"additionalProperties": false
}Fetch one spec clause by id or anchor across `core` / `js-api` / `web-api` (`syntax-numtype`, `valid-unreachable`, `modules`, `streaming-modules`, …): title, prose, cross-references, SpecTec formal refs, and rendered URL.
| Argument | Type | Description |
|---|---|---|
| id* | string | Clause id or anchor. |
| spec | string | Which spec (default core). |
{
"type": "object",
"required": [
"id"
],
"properties": {
"id": {
"type": "string",
"description": "Clause id or anchor."
},
"spec": {
"enum": [
"core",
"js-api",
"web-api"
],
"type": "string",
"description": "Which spec (default core)."
}
},
"additionalProperties": false
}Navigate the clause tree of a spec (`core` / `js-api` / `web-api`), filterable by source `path` (`syntax`, `valid`, `exec`, `binary`, `text`, `appendix`), `anchor_prefix`, `titled_only`, and `max_level`.
| Argument | Type | Description |
|---|---|---|
| path | string | Source path / prefix. |
| spec | string | Which spec (default core). |
| max_level | integer | Cap heading depth. |
| titled_only | boolean | Drop anchor-only blocks. |
| anchor_prefix | string | Id/anchor prefix. |
{
"type": "object",
"properties": {
"path": {
"type": "string",
"description": "Source path / prefix."
},
"spec": {
"enum": [
"core",
"js-api",
"web-api"
],
"type": "string",
"description": "Which spec (default core)."
},
"max_level": {
"type": "integer",
"maximum": 6,
"minimum": 1,
"description": "Cap heading depth."
},
"titled_only": {
"type": "boolean",
"description": "Drop anchor-only blocks."
},
"anchor_prefix": {
"type": "string",
"description": "Id/anchor prefix."
}
},
"additionalProperties": false
}Full-text search across clause anchors, titles, and prose of a spec (`core` / `js-api` / `web-api`). Ranked anchor-exact > title > anchor > prose, with snippets for body matches.
| Argument | Type | Description |
|---|---|---|
| spec | string | Which spec (default core). |
| limit | integer | Max hits. |
| query* | string | Search text. |
{
"type": "object",
"required": [
"query"
],
"properties": {
"spec": {
"enum": [
"core",
"js-api",
"web-api"
],
"type": "string",
"description": "Which spec (default core)."
},
"limit": {
"type": "integer",
"maximum": 100,
"minimum": 1,
"description": "Max hits."
},
"query": {
"type": "string",
"description": "Search text."
}
},
"additionalProperties": false
}Return this server's package version plus the pinned upstream commit SHA(s) the bundled data was indexed from.
No arguments.
{
"type": "object",
"properties": {},
"additionalProperties": false
}Look up a value type (`i32`, `funcref`, `v128`, …) or type form (`functype`, `limits`, `memtype`, …): classification, sibling members, defining clause prose, formal refs, and URL.
| Argument | Type | Description |
|---|---|---|
| name* | string | Type or type-form name. Case-insensitive, exact. |
{
"type": "object",
"required": [
"name"
],
"properties": {
"name": {
"type": "string",
"description": "Type or type-form name. Case-insensitive, exact."
}
},
"additionalProperties": false
}