Function Signature Lookup MCP Server

An MCP server that provides function signature lookups for any API. Uses SQLite database and universal ctags to extract functions and prototypes for indexing source files. Supports all languages that ctags supports including Python, C, Go, C++, JavaScript, Rust, Java, and many others.

• Python 3.13
• Universal Ctags 6.2.0

git clone git@github.com:osinmv/function-lookup-mcp.git
cd function-lookup-mcp
claude mcp add api-lookup $(pwd)/run.sh -s user

Just ask your coding agent to index your header folder. Alternatively, you can generate ctags files manually using universal ctags:

ctags --output-format=json --fields=+Sf --kinds-C=+p -R -f apis/your_api.ctags /path/to/your/headers

Or drop existing ctags files into the apis/ folder and restart the MCP server to update the index.

search_api(function_name: str) - Look up function signatures

list_indexed_apis() - List all indexed API files

list_api_files(api_name: str) - List all unique file paths for a specific API

list_functions_by_file(file_path: str) - List all functions found in a specific file

generate_ctags(include_directory: str, ctags_filename: str) - Generate ctags from header files and add to index