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8 clients · secrets stay placeholders

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{
  "mcpServers": {
    "tc39-mcp": {
      "type": "http",
      "url": "https://mcp.xyzzylabs.ai/tc39/mcp"
    }
  }
}

claude mcp add --transport http tc39-mcp https://mcp.xyzzylabs.ai/tc39/mcp

[mcp_servers.tc39-mcp]
url = "https://mcp.xyzzylabs.ai/tc39/mcp"

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "tc39-mcp": {
      "type": "remote",
      "url": "https://mcp.xyzzylabs.ai/tc39/mcp",
      "enabled": true
    }
  }
}

{
  "mcpServers": {
    "tc39-mcp": {
      "type": "http",
      "url": "https://mcp.xyzzylabs.ai/tc39/mcp"
    }
  },
  "deeplink": "cursor://anysphere.cursor-deeplink/mcp/install?name=tc39-mcp&config=eyJ0eXBlIjoiaHR0cCIsInVybCI6Imh0dHBzOi8vbWNwLnh5enp5bGFicy5haS90YzM5L21jcCJ9"
}

{
  "servers": {
    "tc39-mcp": {
      "type": "http",
      "url": "https://mcp.xyzzylabs.ai/tc39/mcp"
    }
  }
}

{
  "mcpServers": {
    "tc39-mcp": {
      "httpUrl": "https://mcp.xyzzylabs.ai/tc39/mcp"
    }
  }
}

extensions:
  "tc39-mcp":
    enabled: true
    name: "tc39-mcp"
    type: streamable_http
    uri: "https://mcp.xyzzylabs.ai/tc39/mcp"
    timeout: 300

Quality 79 / 100good

protocol75 · weight 25

warn
protocol.modernnewest supported version is 2024-11-05; 2026-07-28 not supported, older versions are deprecated until 2027-07-28
n/a
protocol.statelessonly applies to 2026-07-28 servers
pass
protocol.transportstreamable HTTP
n/a
protocol.list_ttlonly applies to 2026-07-28 servers

authorizationn/a · weight 15

n/a
auth.prm, auth.as_metadata, auth.cimdno remote uses OAuth
n/a
auth.secret_in_urlno templated URL

tool hygiene71 · weight 30

pass
tools.descriptionsevery tool has a description
pass
tools.description_lengthdescriptions are concise
pass
tools.schemasevery tool has an object input schema
fail
tools.annotationsno tool declares readOnlyHint or destructiveHint, so clients cannot tell safe calls from risky ones
fail
tools.directory_hintsno tool declares all four of readOnlyHint, destructiveHint, idempotentHint and openWorldHint; missing: proposal.get (readOnlyHint, destructiveHint, idempotentHint, openWorldHint); spec.about (readOnlyHint, destructiveHint, idempotentHint, openWorldHint); clause.list (readOnlyHint, destructiveHint, idempotentHint, openWorldHint); …
pass
tools.token_costabout 1,882 tokens to load every tool
pass
tools.api_dumptools are not a one-to-one API dump

stability100 · weight 15

pass
stability.changesno tool changes in 30 days
pass
stability.rug_pullno tool changed its meaning under the same name

dependenciesn/a · weight 15

n/a
deps.known_vulns, deps.mcp_sdk_version, deps.resolvabledeps.dev does not know [email protected]

17 tools, about 1,882 tokens to load them all · tool set a0d40b2e18a4 · checked 2026-10-20 15:26 UTC

Tool changes

No tool definition changes recorded. A server's first observation is its baseline; later probes record what changes.

Checks run on what our credential-free, read-only probes observe; tools are never called and no code audit is performed. How it is computed.

Trust 96 / 100

provenance90

liveness98

freshness100

hygiene100

+repository +namespace-matches-repo +website +reachable +uptime-96% +updated-13d-ago

Derived from observable signals (official registry feed and our own credential-free probes); no code audit performed. How it is computed.

Dependencies

[email protected] npmthis version is not known to the dependency resolver

Dependency graphs from deps.dev; advisories from OSV.dev, including the GitHub Advisory Database and the PyPI Advisory Database; all CC BY 4.0. The graph is what a clean install of this version resolves today; nothing was installed or run. How it is checked.

Endpoints

remote	auth	reachable	uptime 30d	p50	protocol	last ok
`https://mcp.xyzzylabs.ai/tc39/mcp` streamable-http	none	yes	96%	258 ms	2024-11-05	2026-10-20

package	registry	version	runtime	secrets
`tc39-mcp`	npm	0.6.4	–

Tools (17)

`clause.get`	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.
`clause.list`	List parsed spec clauses with optional filters (kind, section prefix, has_algorithm). `spec` selects '262' or '402'. `at: '<sha>'` queries a historical main snapshot.
`clause.outline`	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.
`proposal.get`	Fetch one TC39 proposal by slug (exact) or name (case-insensitive).
`proposal.list`	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).
`spec.about`	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.
`spec.crossrefs`	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).
`spec.diff`	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.
`spec.global_search`	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.
`spec.grammar`	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).
`spec.sdo_index`	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).
`spec.search`	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.
`spec.snapshots`	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.
`spec.symbol_resolve`	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.
`spec.tables`	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.
`spec.well_known_intrinsics`	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.
`test262.search`	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`.

Schemas: list_tools.

Similar MCP servers

More from io.github.xyzzylabs

Official server.json

{
  "name": "io.github.xyzzylabs/tc39-mcp",
  "title": "tc39-mcp",
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "remotes": [
    {
      "url": "https://mcp.xyzzylabs.ai/tc39/mcp",
      "type": "streamable-http"
    }
  ],
  "version": "0.6.4",
  "packages": [
    {
      "version": "0.6.4",
      "transport": {
        "type": "stdio"
      },
      "identifier": "tc39-mcp",
      "registryType": "npm"
    }
  ],
  "repository": {
    "url": "https://github.com/xyzzylabs/tc39-mcp",
    "source": "github"
  },
  "websiteUrl": "https://mcp.xyzzylabs.ai/tc39",
  "description": "Independent MCP server for the TC39 specs (ECMA-262 + ECMA-402): clauses, search, diffs, history."
}