tc39-mcp

Self-description of this MCP server: package name + version, per-snapshot pin metadata (sha, fetched_at, biblio_commit, clause_count) for every supported (spec, edition), plus test262 + proposals index headers when present.

{
  "type": "object",
  "properties": {},
  "additionalProperties": false
}

Fetch a parsed TC39 clause as structured JSON. `spec` selects '262' (default) or '402'. `edition` defaults to 'latest'. `at: '<sha>'` pins to a historical main snapshot (only valid for edition='main'); omit to query the live snapshot.

{
  "type": "object",
  "required": [
    "id"
  ],
  "properties": {
    "at": {
      "type": "string",
      "description": "Optional historical SHA pin (hex, 4-40 chars). Only valid when edition='main'; released editions have no per-SHA history to address."
    },
    "id": {
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "edition": {
      "type": "string"
    }
  }
}

List parsed spec clauses with optional filters (kind, section prefix, has_algorithm). `spec` selects '262' or '402'. `at: '<sha>'` queries a historical main snapshot.

{
  "type": "object",
  "properties": {
    "at": {
      "type": "string"
    },
    "kind": {
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "edition": {
      "type": "string"
    },
    "section": {
      "type": "string"
    },
    "has_algorithm": {
      "type": "boolean"
    }
  }
}

Search the parsed spec by clause id / aoid / title (+ step text with `search_steps`). Aoid-exact ranks first. `at: '<sha>'` searches a historical main snapshot.

{
  "type": "object",
  "required": [
    "query"
  ],
  "properties": {
    "at": {
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "query": {
      "type": "string"
    },
    "edition": {
      "type": "string"
    },
    "search_steps": {
      "type": "boolean"
    }
  }
}

List TC39 proposals from the static index (tc39/proposals). Filter by spec ('262'|'402'), stage ('0'|'1'|'2'|'2.7'|'3'|'finished'|'inactive'|'active'), champion (substring), or contains (name/slug substring).

{
  "type": "object",
  "properties": {
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "stage": {
      "type": "string"
    },
    "champion": {
      "type": "string"
    },
    "contains": {
      "type": "string"
    }
  }
}

Fetch one TC39 proposal by slug (exact) or name (case-insensitive).

{
  "type": "object",
  "required": [
    "name"
  ],
  "properties": {
    "name": {
      "type": "string"
    }
  }
}

Query grammar productions captured from the spec's `<emu-grammar>` blocks. `{ nonterminal }` returns every production for that non-terminal (exact match); `{ contains }` filters by RHS / name substring; neither lists all non-terminals + their production counts. `include_sdo` folds in SDO-attached productions (off by default).

{
  "type": "object",
  "properties": {
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "edition": {
      "type": "string"
    },
    "contains": {
      "type": "string"
    },
    "include_sdo": {
      "type": "boolean"
    },
    "nonterminal": {
      "type": "string"
    }
  }
}

List or fetch parsed `<emu-table>` content. `{ id }` returns exactly that table (full columns + rows); otherwise list table summaries, optionally narrowed by a `filter` substring over the caption or id.

{
  "type": "object",
  "properties": {
    "id": {
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "filter": {
      "type": "string"
    },
    "edition": {
      "type": "string"
    }
  }
}

Index Syntax-Directed Operations by the grammar production they're defined on. `by: 'production'` (default) groups SDOs under each production; `by: 'sdo'` groups productions under each SDO title. `filter` narrows to keys containing a substring (case-insensitive).

{
  "type": "object",
  "properties": {
    "by": {
      "enum": [
        "production",
        "sdo"
      ],
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "filter": {
      "type": "string"
    },
    "edition": {
      "type": "string"
    }
  }
}

Return the section tree (table of contents) for a parsed (spec, edition). `depth` caps how deep the tree descends (1 = top-level only); `under` limits the tree to descendants of one clause id.

{
  "type": "object",
  "properties": {
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "depth": {
      "type": "number"
    },
    "under": {
      "type": "string"
    },
    "edition": {
      "type": "string"
    }
  }
}

Run spec.search across both ECMA-262 and ECMA-402 in one call and interleave hits by score. Each hit is tagged with the spec it came from. Use it when you don't know which spec defines a symbol. `search_steps` also matches algorithm step text.

{
  "type": "object",
  "required": [
    "query"
  ],
  "properties": {
    "limit": {
      "type": "number"
    },
    "query": {
      "type": "string"
    },
    "search_steps": {
      "type": "boolean"
    }
  }
}

List the live (spec, edition, sha, fetched_at) snapshots the hosted Worker is serving from R2. Filter by `spec` ('262'|'402') or `edition` (e.g. 'main', 'es2026'). Historical SHA-pinned copies are reachable via `at:` on clause.get / spec.search but aren't enumerated here.

{
  "type": "object",
  "properties": {
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "edition": {
      "type": "string"
    }
  }
}

Resolve spec notation like `[[Prototype]]` (internal slot), `%Object.prototype%` (well-known intrinsic), or `~number~` (sigil enum): return clauses that mention or define it, ranked by occurrence with a bump for definition-y sections.

{
  "type": "object",
  "required": [
    "notation"
  ],
  "properties": {
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "edition": {
      "type": "string"
    },
    "notation": {
      "type": "string"
    }
  }
}

Enumerate the well-known intrinsics in a spec with their probable defining clauses. Driven from the canonical §6.1.7.4 WKI table when present (ECMA-262), else a `%X%` prose scan (e.g. ECMA-402). `filter` narrows by bare-name substring.

{
  "type": "object",
  "properties": {
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "filter": {
      "type": "string"
    },
    "edition": {
      "type": "string"
    }
  }
}

Clause-level diff of one clause across two editions of a spec. Reports identical / modified / added / removed plus a field-level breakdown (title, signature, step count, reworded step indices, notes, crossrefs). `from` defaults to the latest stable release, `to` to main.

{
  "type": "object",
  "required": [
    "id"
  ],
  "properties": {
    "id": {
      "type": "string"
    },
    "to": {
      "type": "string"
    },
    "from": {
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    }
  }
}

For a clause id, return its outgoing references (clauses it cites) and/or incoming references (clauses that cite it — the back-reference index the parse alone doesn't expose). The reverse index is AOID-densified from step text. `direction`: 'in' | 'out' | 'both' (default). Outgoing also carries an `external` category: the clause's citations to external specs (Unicode, IETF, WHATWG) as resolvable URLs. Set `include_cross_spec: true` to also resolve outgoing references from ECMA-262 → ECMA-402 (or vice versa).

{
  "type": "object",
  "required": [
    "id"
  ],
  "properties": {
    "id": {
      "type": "string"
    },
    "spec": {
      "enum": [
        "262",
        "402"
      ],
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "edition": {
      "type": "string"
    },
    "direction": {
      "enum": [
        "in",
        "out",
        "both"
      ],
      "type": "string"
    },
    "include_cross_spec": {
      "type": "boolean"
    }
  }
}

Search the tc39/test262 conformance suite from its indexed front-matter. `query` AND-matches whitespace tokens (case-insensitive) across each test's description + path; `esid` prefix-matches the front-matter esid. Returns ranked hits (path, GitHub url at the indexed SHA, esid, description, features, flags), capped at `limit` (default 20). Supply at least one of `query` / `esid`.

{
  "type": "object",
  "properties": {
    "esid": {
      "type": "string"
    },
    "limit": {
      "type": "number"
    },
    "query": {
      "type": "string"
    }
  }
}

Advertised by the server during the last successful anonymous check.

Walk through a TC39 clause: call spec.about for pins, clause.get for the full clause, then explain the algorithm steps in plain language with citations.

id

Clause id, e.g. sec-tonumber or sec-intl.numberformat (required)

spec

Spec to read: '262' (default) or '402'

edition

Edition alias or concrete edition (latest, main, es2026, …)

Advertised by the server during the last successful anonymous check.

Diff one clause across two editions via spec.diff, then optionally clause.get on each side for full step text. Summarize what changed and why it might matter.

id

Clause id to compare (required)

spec

Spec: '262' (default) or '402'

from

Before edition (default: latest)

to

After edition (default: main)

Advertised by the server during the last successful anonymous check.

Search for a clause by name/symptom (spec.search or spec.global_search), pick the best hit, then clause.get and summarize.

query

Search string (AOID, title fragment, or symptom) (required)

spec

Limit to one spec ('262' or '402'). Omit to search both via spec.global_search.

edition

Edition for the search/read (default: latest)

search_steps

If 'true', also match algorithm step text (slower, broader)

Advertised by the server during the last successful anonymous check.

Map who a clause cites and who cites it via spec.crossrefs, then spot-check key neighbors with clause.get.

id

Clause id to start from (required)

spec

Spec: '262' (default) or '402'

edition

Edition (default: latest)

direction

in | out | both (default: both)

include_cross_spec

If 'true', also resolve 262↔402 outgoing refs

Advertised by the server during the last successful anonymous check.

Look up TC39 proposal stage/champions via proposal.list and/or proposal.get, then summarize maturity and where to read more.

query

Proposal slug (preferred) or name/substring, e.g. temporal or 'pipeline operator' (required)

stage

Optional stage filter for list: 0|1|2|2.7|3|finished|inactive|active

Advertised by the server during the last successful anonymous check.

Find test262 coverage via test262.search (and test262.get on stdio for full source). Summarize how the feature is tested.

query

Free-text search (feature name, path fragment, …)

esid

Clause id / esid prefix (e.g. sec-tonumber)

Advertised by the server during the last successful anonymous check.

Produce a citation block with SHA pins: call spec.about, then clause.get, and format a reproducible reference (spec, edition, sha, clause id/number/title).

id

Clause id to cite (required)

spec

Spec: '262' (default) or '402'

edition

Edition (default: latest)