io.github.harshithsunku/mcp-gtags-server

What does this function call? Callees / outgoing calls of a function. Shows a function's dependencies without reading any file: call sites are detected in its body and verified against the index, split into in-tree functions (with locations) and external/unresolved names. Macro-generated and parser-missed (EXPORT_SYMBOL-recovered) definitions resolve too, flagged resolved_via. JSON results: {in_tree: [{symbol, path, line}], external: [names]}. Args: symbol: Exact name of the function to analyze.

Who calls this function? Callers / call hierarchy / incoming calls, deduplicated per calling function with call counts. Each reference is mapped to its enclosing function and shown with the source line of its first call site, so there is nothing to re-grep. The highest signal-to-noise "who uses this?" view for impact analysis; iterate it to walk the caller graph upward. JSON results: {caller, path, sites, call} items (call = source of the first site). Args: symbol: Exact symbol name whose callers you want.

Go to definition: where a C/C++ symbol (function, struct, macro, typedef, enum) is defined, with a usage summary — the best first query. Each definition carries its #if/#ifdef guard stack (several guarded definitions = a config choice) and ctags kind/signature. The summary gives reference and file counts, the hottest files and the EXPORT_SYMBOL* variant. Macro-generated symbols resolve ("sys_read" -> SYSCALL_DEFINE3(read, ...), DEFINE_SPINLOCK names), and definitions the index parser missed are recovered from their EXPORT_SYMBOL* site — both flagged resolved_via. A miss suggests similarly named symbols. JSON: results are {symbol, path, line, col, kind, typeref, scope, signature, guard, snippet} records; the envelope adds definition_count, guard_variants, reference_count, file_count, top_files, exported. Args: symbol: Exact symbol name, e.g. "tcp_v4_rcv". case_insensitive: Match ignoring case (skips the usage summary). active_config: Kernel .config path or macro list like "CONFIG_SMP,BITS_PER_LONG=64,!CONFIG_DEBUG"; drops definitions whose guard stack is definitely false under it (count reported as config_filtered). Unknown macros never drop anything.

Find all references / usages of a C/C++ symbol — every call and use site. Only real reference sites from the index, each with its #if/#ifdef guard stack. Very widely used symbols (more than 200 sites, e.g. kmalloc) come back grouped by file with counts — see where usage concentrates, then narrow with path_prefix. Symbols with no in-tree definition (libc calls, some variables) work too, flagged "fallback": "symbol_usages". Args: symbol: Exact symbol name. case_insensitive: Match ignoring case. active_config: Kernel .config path or macro list; drops references whose guard stack is definitely false under it (config_filtered). group_by: "auto" (default: per-file counts above 200 references), "line" (always individual sites) or "file" (always per-file counts). path_prefix: Only references under this directory, e.g. "fs/ext4".

Read a symbol's source: the full body of a function, struct or macro definition, without reading the whole file. Extracts only the definition's lines, so a one-screen function never costs a 5000-line file read. Macro-generated and parser-missed (EXPORT_SYMBOL-recovered) definitions resolve too, flagged resolved_via. JSON results: {path, line, body} items. Args: symbol: Exact symbol name. max_definitions: Return at most this many bodies when the symbol is multiply defined (default 3).

Outline of one source file: every function, struct and macro it defines (document symbols), with kind, signature and #ifdef guards. Use this INSTEAD of reading a file when you only need its API surface. Args: file_path: Source file, relative to the project root or absolute.

Call path / call chain: does FROM transitively call TO, and through which functions? Use this instead of chaining find_callers rounds when the question is "can this function end up in that one?". BFS over the caller graph returns the SHORTEST chain, each hop with the call site's file:line. JSON results: {path_found, hops, depth, nodes_explored}; hops run from from_symbol to to_symbol. Static analysis cannot follow function pointers (ops structs, callbacks). Args: from_symbol: The caller end ("can this reach ..."). to_symbol: The callee end ("... this function?"). max_depth: Longest chain to consider, in calls (1-12, default 8).

Refresh the code index synchronously after editing files — the guaranteed-freshness barrier. Query tools refresh the index automatically in the background, so results can lag very recent edits by a few seconds. Call this right after editing files when the very next query must see the changes. Args: full: Rebuild the index from scratch instead of refreshing it incrementally (rarely needed — large branch switch, suspected corruption).