Give me a type signature and I shall move the world.

mcp-hoogle

An MCP (Model Context Protocol) server that exposes Hoogle search over your project's local Haskell dependencies. Run it from within your project's nix-shell to give AI assistants type-aware search across all your project's packages.

Usage

1. Generate a Hoogle database from your project

From within your project's nix-shell (where all dependencies are available):

mcp-hoogle generate

This indexes all packages in your local GHC package database.

2. Run the MCP server

mcp-hoogle serve

Or with a specific database path:

mcp-hoogle serve /path/to/database.hoo

3. Configure Claude Code

Add to your Claude Code MCP settings:

{
  "mcpServers": {
    "hoogle": {
      "command": "mcp-hoogle",
      "args": ["serve"]
    }
  }
}

MCP Tools

The server exposes four tools:

• search — Search by function name, type signature, or keyword
• search_type — Search specifically by type signature (e.g. [a] -> Int)
• lookup_module — Browse exports of a module (e.g. Data.Map)
• regenerate_database — Re-index packages and reload without restarting the server

Building

nix-shell
cabal build

Or via nix:

nix-build

How it works

1. mcp-hoogle generate calls hoogle generate --local which indexes all packages registered in the current GHC package database
2. mcp-hoogle serve loads the generated Hoogle database and exposes it via MCP stdio transport
3. AI assistants connect via MCP and can search for types, functions, and modules