mcp-gtags-server

Every AI coding agent answers “where is this function defined?” the same way: grep the entire tree. On a full Linux kernel checkout — 65,163 files, 37.1 million lines — that’s 1.6 seconds and 7,873 noisy match lines for kmalloc. This server answers the same question in 10 ms with 5 lines, by exposing GNU Global’s index to any MCP client (Claude Code, Cursor, Claude Desktop) through 11 tools: definitions, references, callers/callees, function bodies, reachability chains, and a blast_radius tool that ranks what an uncommitted diff impacts.

It’s built for the codebases LSP tools can’t handle: trees that don’t compile, machines without sudo, kernel-scale C/C++. The hard parts are the kernel-isms — #ifdef guard stacks filtered against a .config, macro-generated symbols (sys_read resolved to its SYSCALL_DEFINE3 site), and definitions gtags’ parser derails on recovered via their EXPORT_SYMBOL site with ctags. Index management is invisible: the first query builds it (66 s for the whole kernel), every query incrementally refreshes it in under a second.

Correctness is measured, not assumed: CI runs a 65-case golden eval against a pinned kernel v6.16 on every push — currently 100% recall and 100% precision@1 across all 11 tools. Install is one user-level config entry (uvx mcp-gtags-server); the whole toolchain bootstraps itself into user space on first use.