Callimachus MCP Server

Most developer tooling work still happens through a UI a human drives. Callimachus MCP server moves it into the conversation instead. MCP server for Callimachus: local index and search of your AI coding-agent threads.

The short version

Named for Callimachus, who built the first catalogue of the Library of Alexandria.

• Indexes — every conversation from 11 coding agents into one local SQLite store — Claude Code, Codex, Cursor, Gemini CLI, Qwen Code, Goose, OpenCode, Continue, Cline, Roo Code, and Kilo Code. Adding another source is a small, documented contract
• Searches — them with hybrid ranking: keyword (SQLite FTS5 / BM25) fused with on-device semantic similarity (sqlite-vec KNN, no cloud) via Reciprocal Rank Fusion. Filter by source, project, subagents, starred, and tags
• Finds code-aware — — type file:embed/mod.rs in the search bar (or cal files ) to find every thread that touched a path; backed by a file-mention index built at index time
• Curates the facts — — pin, edit, or delete distilled facts so your edits survive re-distilling, plus an LLM "Review conflicts" pass that flags decisions that contradict each other
• Asks your history (RAG) — — a synthesized, cited answer over your own threads, with [thread N] citations back to the sources it used. Needs an LLM engine (Knowledge/distillation enabled)
• Organizes into collections — — star threads and attach free-form tags, then filter the list by starred or by tag

The tools it exposes

The server publishes 8 tools. What each one is for:

• Shell — ** Tauri 2 (Rust) + React 19 + TypeScript + Vite 8
• Watcher — ** notify + debouncer
• Chat — ** multi-provider via the genai crate (Anthropic / OpenAI / Gemini / OpenRouter / Ollama local + Ollama Cloud), each with a configurable base URL
• Secrets — ** OS credential store via the cross-platform keyring crate — macOS Keychain, Windows Credential Manager, Linux Secret Service
• Sidecars — ** callimachus-mcp (MCP server) and cal (CLI) — both reuse the desktop core lib against the same index.db
• Editor — ** a VS Code / Cursor extension (apps/vscode, published to the Marketplace + Open VSX) that shells out to cal
• Cross — platform (macOS / Windows / Linux). The only macOS-only piece left is the "Open in CLI" / "Resume" launchers (they drive Terminal via AppleScript)
• Tests — The --ignored tests touch live data on this machine: each source has a real__index smoke test that indexes your real history read-only

Getting it running

The server ships on npm as callimachus-mcp, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.

How it compares

This sits in the developer tooling group, where several servers overlap in what they claim to do but differ sharply once you actually set them up. Callimachus's toolset — Shell, Watcher, Chat and 5 more — is a fair guide to whether it matches your workflow. It is maintained by BetaBots-LLC; worth a glance at recent repository activity before you build anything load-bearing on it.

We check each listing at SyncDev against the project's documentation before it goes live — if something here drifts out of date, it is a bug worth reporting.

Things to watch

• It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
• Keep per-call confirmation enabled while you learn its behaviour; it is the cheapest safeguard you have.