wasm-mcp MCP server

A read-only MCP server providing structured access to the WebAssembly specification, including instructions, types, sections, and proposals. It offers deterministic, SHA-pinned data indexed from the WebAssembly/spec repository, allowing AI agents to query spec details via tools like instruction_get, type_get, and spec_search without executing code.

Endpoint and access

No sign-in: your client connects and lists tools immediately, with no account or key.

No sign-inEndpoint checked 2026-10-05Operated by xyzzy_labs

MCP endpoint (Streamable HTTP)

https://mcp.xyzzylabs.ai/wasm/mcp

Vendor documentation

What you can do with it

Lookup WebAssembly instruction mnemonics and opcodes
Retrieve structured type signatures and categories
Search specification sections and proposals
Get anchor-addressable spec clauses with cross-references

Tools advertised by the last live check:

spec_version
instruction_get
instruction_list
instruction_search
type_get
section_get
section_list
spec_search
proposal_list

Connect from your client

Each snippet registers the same endpoint; pick the client you 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.

Claude Code

Run this once in a terminal. It registers a Streamable HTTP server. Use --scope project to write .mcp.json for the repo.

Claude Code configuration

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

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).

Codex configuration

codex mcp add wasm-mcp --url https://mcp.xyzzylabs.ai/wasm/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable wasm-mcp in your MCP settings.

Cursor configuration

{
  "mcpServers": {
    "wasm-mcp": {
      "url": "https://mcp.xyzzylabs.ai/wasm/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure). The type must be streamableHttp for a remote HTTP server.

Cline configuration

{
  "mcpServers": {
    "wasm-mcp": {
      "type": "streamableHttp",
      "url": "https://mcp.xyzzylabs.ai/wasm/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start wasm-mcp and inspect its tools.

VS Code configuration

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

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.

Gemini CLI configuration

gemini mcp add --transport http wasm-mcp https://mcp.xyzzylabs.ai/wasm/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.

Claude Desktop configuration

{
  "mcpServers": {
    "wasm-mcp": {
      "url": "https://mcp.xyzzylabs.ai/wasm/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.

Windsurf configuration

{
  "mcpServers": {
    "wasm-mcp": {
      "serverUrl": "https://mcp.xyzzylabs.ai/wasm/mcp"
    }
  }
}

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