tc39-mcp

An independent MCP server providing structured, read-only access to TC39 specifications (ECMA-262 and ECMA-402). It enables AI agents to perform clause lookups, search by AOID, view cross-spec references, compare edition diffs, and access git history using deterministic, SHA-pinned JSON data. The server supports local stdio execution with offline caching or hosted HTTP access.

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Package and access

Local package with source-attributed installation metadata. Koskamo does not execute packages during review.

Community listingLocal stdioSource reviewed; not executedPublished by xyzzy_labs

Vendor documentation

What you can do with it

Retrieve structured JSON for specific ECMAScript clauses
Search specifications by AOID or global terms
Compare differences between ECMAScript editions
Resolve cross-references between ECMA-262 and ECMA-402

Source and maintenance

Community listingRegistry 0.6.4

mcp-registry: io.github.xyzzylabs/tc39-mcp@0.6.4 Source repository Project website

Maintenance checked: Oct 31, 2026, 10:27 PM UTC

Packages and installation

Source-provided package data. Koskamo has not executed or live-probed this package.

tc39-mcp 0.6.4

npm

tc39-mcp package definition

{
  "version": "0.6.4",
  "transport": "stdio",
  "identifier": "tc39-mcp",
  "registryType": "npm"
}

Tools

Reported by the attributed source; not independently observed by Koskamo.

No tool definitions available.

Connect from your client

Each snippet configures the same source-provided package; replace placeholders before use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Cursor

Merge this local stdio configuration, replace every placeholder environment value, and restart Cursor. Koskamo has not executed this package.

Cursor configuration

{
  "mcpServers": {
    "tc39-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "tc39-mcp@0.6.4"
      ]
    }
  }
}

Cline

Merge this local stdio configuration, replace every placeholder environment value, and restart Cline. Koskamo has not executed this package.

Cline configuration

{
  "mcpServers": {
    "tc39-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "tc39-mcp@0.6.4"
      ]
    }
  }
}

VS Code

Merge this local stdio configuration, replace every placeholder environment value, and restart VS Code. Koskamo has not executed this package.

VS Code configuration

{
  "servers": {
    "tc39-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "tc39-mcp@0.6.4"
      ]
    }
  }
}

Claude Desktop

Merge this local stdio configuration, replace every placeholder environment value, and restart Claude Desktop. Koskamo has not executed this package.

Claude Desktop configuration

{
  "mcpServers": {
    "tc39-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "tc39-mcp@0.6.4"
      ]
    }
  }
}

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