callimachus — Claude Code MCP server: what it does, how to install
Indexes local chat transcripts across 11 AI coding assistants and exposes them via search. Helps agents recall earlier decisions without repeating mistakes.
claude mcp add callimachus -- npx -y callimachus-mcpWhat callimachus does
The server links your agent to Callimachus's local SQLite catalog. The background indexer monitors logs from 11 development tools, including Claude Code, Cursor, and Codex. Search fuses keyword hits from SQLite FTS5 with local sqlite-vec vector embeddings on your hardware. Everything remains strictly on the machine.
Through MCP, the agent interacts with past context in both directions. It queries threads by touched file paths, checks prior agreements via check_decision, and correlates git commits with the sessions that authored them. Agents can also write back into local storage, closing open action items or capturing session snapshots without modifying repo files.
Running the integration requires npx in your environment. Distilling takeaways and summaries works with a local Ollama instance or an active subscription in supported CLI agents. Without a configured language model, automated fact extraction stays disabled. The source is published under the AGPL-3.0 license.
What it helps with
- locate previous discussions affecting a specific file path
- verify past architectural decisions before rewriting code
- attribute git commits to specific agent transcripts
- snapshot session context across agent compaction boundaries
Example prompts for the agent
- Search Callimachus history for earlier discussions about database migrations.
- Check settled decisions regarding authentication before changing this route.
- Save a session snapshot with our current progress to project memory.
How to install callimachus
Platform CLI
claude mcp add callimachus -- npx -y callimachus-mcpPlatform CLI
codex mcp add callimachus -- npx -y callimachus-mcpConfig file
{
"mcpServers": {
"callimachus": {
"command": "npx",
"args": [
"-y",
"callimachus-mcp"
]
}
}
}Config file
{
"servers": {
"callimachus": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"callimachus-mcp"
]
}
}
}Platform CLI
gemini mcp add callimachus npx -y callimachus-mcpStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about callimachus
How to install callimachus in Claude Code?
Run claude mcp add callimachus -- npx -y callimachus-mcp in your terminal. This registers the server tools directly with Claude Code.
What does callimachus do?
It indexes conversational threads from various coding agents into a local SQLite database. Agents query this history to retrieve past bug solutions, architectural rationale, and file-level edits.
Does callimachus send transcripts to external servers?
All indexing, keyword searches, and embeddings run entirely on your local machine. External requests happen only if you explicitly point summarization to a cloud model provider.
