№ 04 — MCP server

Give every agent a memory.

callimachus-mcp exposes your local history to any MCP client through twenty-one tools — and now reads and writes the memory layer. Instead of re-explaining context, your agent can look it up: searching past sessions, recalling settled decisions and known gotchas, asking your history a cited question, linking threads to the git commits they produced, and pulling the exact thread it needs. It can also write back — closing TODOs, recording new decisions and gotchas, and snapshotting a session for handoff across a context-window compaction or another tool — but only ever touches Callimachus's own index and memory, never your files.

Install & connect

Install the desktop app — it ships callimachus-mcp on your PATH. Then register it with your client:

$ claude mcp add callimachus -- callimachus-mcp

Or build from source

from a checkout of the repo

$ cargo install --path apps/desktop/src-tauri --bin callimachus-mcp

Reads the same local index as the app — no separate database, no extra indexing. Ships a /recall skill that teaches agents when to reach for it.

Tools it exposes

search_threadsKeyword + optional semantic search of the whole index
search_current_projectScope search to the launching repo
recent_threadsThe most recently updated threads
get_threadFetch a full thread as a packed transcript
list_tagsDiscover the user's tags / collections
list_open_todosUnfinished TODOs across past sessions (no key needed)
get_thread_knowledgeDistilled summary, decisions, gotchas for a thread
recall_decisionsSemantically recall past decisions and why
recall_gotchasSemantically recall known pitfalls to avoid
find_prior_workPrior sessions similar to a task — the 'have I done this?' guard
project_memoryA project's durable memory: decisions, gotchas, open TODOs
ask_historyA synthesized, cited answer over your own history (RAG)
threads_for_fileWhich past sessions touched a file path
check_decisionSurface settled decisions before re-litigating a proposal
linked_commitsThe git commits a thread likely produced
list_snapshotsResumable session snapshots for a project
load_snapshotLoad a snapshot's packed transcript + carry-forward memory
complete_todowriteMark an open TODO done — persists across re-index
record_decisionwritePersist a decision (with optional rationale) into memory
record_gotchawritePersist a gotcha into a project's memory
snapshot_sessionwriteCheckpoint a thread for handoff across compaction or tools

Seventeen read tools and four write tools (complete_todo, record_decision, record_gotcha, snapshot_session) that update Callimachus's own memory — never your project files.