Montycat MCP — Shared Memory for AI Agents

A self-hosted MCP server that gives AI agents persistent, searchable memory.
Claude, Codex, Cursor, and any Model Context Protocol client write to one
memory and read each other's.

Memory that survives the chat. Decisions, preferences, and project context carry into the next session.
One memory, many agents. Every MCP client you use works from the same facts.
Recall by meaning, keyword, or both. Vector search finds a memory when the wording differs, BM25 nails exact identifiers, and hybrid mode fuses the two. Exact-key and metadata lookup too.
Yours. Server, engine, and embeddings run on your machine. No hosted memory service, no cloud embedding API.

Install

Claude Desktop — download the latest .mcpb from
Releases and
drag it into Claude Desktop. No Python needed.

Claude Code — install uv, then:

/plugin marketplace add MontyGovernance/montycat-mcp
/plugin install montycat-mcp@montygovernance

/mcp confirms the montycat server is connected.

Codex, Cursor, other MCP clients — point your client's stdio config at
uvx montycat-mcp (Python 3.10+). For Codex:

codex mcp add montycat -- uvx montycat-mcp

The engine

Memory lives in a Montycat Semantic engine.
Montycat MCP starts a local one for you, so most people can stop reading here.

Point it at an engine you already run:

export MONTYCAT_URI="montycat://memory-agent:password@localhost:21210/memories"
export MONTYCAT_TLS=true   # remote engines only

Or start one yourself with Docker:

docker run -d --name montycat -p 21210:21210 -p 21211:21211 \
  -e MONTYCAT_SUPEROWNER=admin -e MONTYCAT_PASSWORD=change-me \
  -v montycat_data:/var/lib/.montycat \
  montygovernance/montycat:semantic

On Apple Silicon use the arm64-semantic tag instead — semantic is the amd64
image, and it crashes under emulation. Port 21211 carries live memory watches.

Use it

Talk to your agent normally; it picks the tool.

Remember that the team chose PostgreSQL for the billing service.

What did we decide about the billing database?

Save this to the shared engineering scope.

scope decides where a memory lives — alice for private, engineering for a
team, shared for common. It is a namespace, not a security boundary: for real
isolation, give each MCP server its own least-privilege Montycat credential.

Tools

Need	Tools
Store	`montycat_remember`, `montycat_remember_bulk`, `montycat_update`, `montycat_forget`
Recall	`montycat_semantic_search`, `montycat_recall`, `montycat_list_memories`
Collaborate	`montycat_await_memory_change` — wait for another agent's write, no polling
Namespaces	`montycat_list_keyspaces`, `montycat_create_keyspace`, `montycat_remove_keyspace`
Admin	semantic index, snapshot, and policy tools — see the plugin guide

Destructive tools are declared as such, so your client's confirmation prompts apply.

Configuration

Variable	Purpose
`MONTYCAT_URI`	Connection string: `montycat://user:password@host:port/store`
`MONTYCAT_TLS`	`true` for a remote TLS engine
`MONTYCAT_DEFAULT_KEYSPACE`	Memory namespace; `memory` by default
`MONTYCAT_SCOPE`	Default scope when a call omits one
`MONTYCAT_AUTO_PROVISION`	Create a permitted scope on first use; `true` by default
`MONTYCAT_AUTOSTART`	`off` to require an already-running engine

Compose setup and the full variable list: compose.yaml and the
plugin guide.

Changelog · Privacy · Issues · Docs · Docker Hub

Existing MemoCat installs keep working: memocat-mcp, MEMOCAT_*, and
memocat:// are still supported. New setups should use the Montycat names.

MIT

montycat-mcp