Locus

Lightweight MCP for LSP navigation

Locus gives your AI coding agent a map of your codebase — definitions, references, types, and diagnostics — through six focused MCP tools. Install with npx. Your host still edits files; Locus only reads structure.

Why lightweight

Most agent IDE stacks expose dozens of MCP tools, symbolic editing, and session memory. Locus does one job: semantic navigation backed by language servers. Six tools, compact line-oriented output, no second IDE inside MCP.

Smaller tool surface means less context for the agent to juggle and faster calls when you only need to find a definition or list callers. That is the performance story — fewer moving parts, not invented benchmarks.

Install

npx @paladini/locus-mcp init
npx @paladini/locus-mcp check

Add the MCP server to Cursor, Codex, or Claude Code. Node.js 22+ required. Language servers on your PATH for the languages you use.

Six tools

locate
Find a symbol by name or list symbols in a file.
refs
All references or implementations at a position.
hover
Type information and documentation.
diagnostics
File or workspace errors and warnings.
status
Language-server readiness and missing binaries.
rename
Preview a rename (dry-run; apply via your agent).

When to choose Locus

Locus Serena Grep
Goal Navigation + diagnostics Full agent IDE (edit, refactor, memory) Text search
MCP tools 6 fixed Many —
Install npx @paladini/locus-mcp uv tool install serena-agent Host built-in
Edits code No — host edits Yes — symbolic editing No
Output Compact lines Mixed Text matches

Choose Locus when your agent host already handles edits and you want definitions, references, types, and diagnostics on demand. Choose Serena when you need symbolic editing and memory inside MCP. Use grep for strings, logs, and comments — Locus targets typed symbols.

What Locus does not do

Links