mcp-registry-finder

Search the official MCP Registry from inside your agent session.

An MCP server that wraps the official Model Context Protocol Registry REST API as MCP tools — so a Claude Code / Claude Desktop / Cursor session can find, inspect, and get install commands for published MCP servers without you tabbing over to a browser.

github.com/bharat3645/mcp-registry-finder · MIT · built by Bharat

The problem

By mid-2026 the MCP server ecosystem is large and fragmented: the official registry alone lists thousands of published servers, and third-party directories (mcp.so, LobeHub, and others) each index tens of thousands more, with no single, consistent way to search. If you're inside an agent session and want to know "is there already an MCP server for X" or "what's the exact install command for that GitHub MCP server," today you leave the chat, open a browser, and search a directory by hand.

This is the missing meta-tool: an MCP server whose whole job is making the official registry queryable from inside the session that would actually use the result.

Related MCP server: mcp-server-mcpindex

What it is

Four tools, each doing one job:

It talks to the official registry only (registry.modelcontextprotocol.io, the registry stood up under the modelcontextprotocol/registry project) — not the larger unofficial directories, which have no single stable API.

Install

Claude Code

claude mcp add registry-finder -- npx -y mcp-registry-finder

Claude Desktop / other MCP hosts

Add to your MCP config (e.g. claude_desktop_config.json):

{
  "mcpServers": {
    "registry-finder": {
      "command": "npx",
      "args": ["-y", "mcp-registry-finder"]
    }
  }
}

Run from source

git clone https://github.com/bharat3645/mcp-registry-finder && cd mcp-registry-finder
npm test           # 40 tests, node:test, zero test-framework dependencies
npm start           # runs the stdio server directly

There is nothing to build — the package ships as plain ESM JavaScript and has zero runtime dependencies: it uses Node's built-in global fetch (Node ≥18) and node:readline for the stdio transport.

Example

Once installed, ask your agent things like:

"Is there an MCP server for Slack in the official registry?" "Give me the install command for the filesystem MCP server." "What's been published to the registry in the last 3 days?"

which route to search_registry, search_registry + get_server_details, and list_recent_servers({ updatedWithinDays: 3 }) respectively.

Architecture

stdin ──► readline (newline-delimited JSON-RPC) ──► server.js (protocol) ──► tools.js ──► registryClient.js ──► registry.modelcontextprotocol.io
stdout ◄── JSON-RPC responses                    ◄──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

• src/server.js — transport-agnostic JSON-RPC message handling (initialize, ping, tools/list, tools/call), so protocol logic is unit-testable without spawning a process.

• src/index.js — the stdio transport shim: one JSON-RPC message per line in, one per line out, logs on stderr only, per the stdio transport spec.

• src/registryClient.js — thin fetch wrapper over the registry's /v0 endpoints, with an injectable fetchImpl for testing.

• src/tools.js / src/format.js — tool schemas/handlers and pure formatting helpers (install-command derivation, summaries).

Targets protocol versions 2025-06-18 and 2025-03-26 (negotiated at initialize, defaulting to 2025-06-18). The registry's own transport (Streamable HTTP for remote servers, stdio/HTTP for local packages) is unrelated to this server's own transport, which is always stdio.

Verification

• 40 tests on node:test, zero test-framework dependencies (npm test).

• registryClient and tools are unit-tested against real recorded responses captured from the live registry API on 2026-07-10 (see fixtures/) via an injected fetch, covering success, 404, non-JSON, and network-failure paths.

• format.js (install-command derivation, summaries) is pure and exhaustively unit-tested — npm, pypi (uvx and pip variants), oci, nuget, cargo, mcpb, and the unrecognized-type fallback.

• test/protocol.test.js spawns the real server binary and drives it over actual stdin/stdout pipes — a genuine end-to-end test of the JSON-RPC framing, restricted to the tools that need no network (initialize, ping, tools/list, format_install_command) so the suite never depends on internet access being available wherever it runs.

• node --check passes on every source and test file.

Scope, stated plainly

• Read-only. The registry API also defines optional publish / update / delete endpoints gated by bearer auth; this server doesn't implement them — it's a finder, not a publisher.

• No live-network integration test ships in this repo. The registry client's HTTP-calling code is unit-tested against real, recorded API responses (not live calls) so the suite is deterministic and runs offline; the request/response shapes were hand-verified against the live registry while building this. If the registry changes its response shape, the unit tests won't catch that on their own — recapture the fixtures under fixtures/ from a live GET /v0/servers call to re-verify.

• Targets the stable spec, not the bleeding edge. The registry's own API doc set references both a deployed /v0 path and a documented /v0.1 OpenAPI schema; this client targets the deployed /v0 path (verified live) and exposes baseUrl as an override (MCP_REGISTRY_FINDER_BASE_URL) in case that changes. Likewise, this server negotiates the current stable MCP protocol versions (2025-06-18 / 2025-03-26), not the 2026-07-28 stateless-protocol release candidate, since that RC isn't final or widely supported by hosts yet.

• Substring search only. search_registry matches on server name, which is what the registry's search query parameter does server-side — there's no fuzzy or semantic matching layer on top.

License

MIT.