Ultramemory MCP Server

UltraMemory — cross-tool memory for your AI

One memory across Claude Code, Claude Desktop, claude.ai, Cursor, ChatGPT, and Hermes. Recalls first every turn — and is honest enough to say "I don't know" instead of making things up.

UltraMemory is a hosted, multi-tenant agent-memory service. One API key (um_…) = your own private tenant. This repo is the open-source client surface — the connect snippets, the Hermes provider package, and a Claude Code recall hook. They all just call the hosted API at https://api.ultramemory.us; the engine stays a managed service (open-core).

Quick start

claude mcp add --transport http ultramemory https://api.ultramemory.us/mcp \
  --header "Authorization: Bearer um_YOUR_KEY"

Get a free key at https://ultramemory.us — no credit card required.

Tools

The MCP server (https://api.ultramemory.us/mcp, Streamable HTTP) exposes six tools:

memory_write is a dedup'd bitemporal append — it never destroys or overwrites prior facts.

Connect any client

Endpoint: https://api.ultramemory.us/mcp (Streamable HTTP) · Auth: Authorization: Bearer um_<key>

Claude Code (CLI):

claude mcp add --transport http ultramemory https://api.ultramemory.us/mcp \
  --header "Authorization: Bearer um_YOUR_KEY"

Cursor / generic mcp.json:

{ "mcpServers": { "ultramemory": {
  "url": "https://api.ultramemory.us/mcp",
  "headers": { "Authorization": "Bearer um_YOUR_KEY" }
}}}

Claude Desktop (mcp-remote bridge):

{ "mcpServers": { "ultramemory": {
  "command": "npx",
  "args": ["mcp-remote@latest", "https://api.ultramemory.us/mcp",
           "--header", "Authorization: Bearer um_YOUR_KEY"]
}}}

Hermes:

pip install ultramemory-hermes
ultramemory enable --key um_YOUR_KEY

ChatGPT: Settings → Apps & Connectors → Developer Mode → Create → URL https://api.ultramemory.us/mcp → Auth = API key. (Plus/Pro = recall-only.)

curl / REST:

curl -s -X POST https://api.ultramemory.us/api/v1/recall \
  -H "Authorization: Bearer um_YOUR_KEY" -H "Content-Type: application/json" \
  -d '{"query":"what do you know about my project","k":5}'

Hermes deep integration

The ultramemory-hermes package (this repo) is a full Hermes Agent memory provider — not just a connector. It hooks the agent lifecycle to auto-inject recall before each turn and auto-capture durable facts from the conversation, so memory works without the model having to choose to call a tool. Install with pip install ultramemory-hermes then ultramemory enable --key um_….

Claude Code recall hook

Want deterministic recall in Claude Code without Hermes? Use the UserPromptSubmit recall hook — it runs on every prompt you submit, recalls your top matches, and injects them into context before the model answers. Fail-open and copy-paste runnable. See hooks/README.md.

Why UltraMemory

• Deterministic recall-first. "Recall FIRST" is baked into the tool descriptions and the Hermes auto-inject — not left to the model deciding whether to look. Recall-first, guaranteed.
• Honest about what it doesn't know. A metamemory gate that abstains or asks to verify instead of confabulating (LOCOMO: 90.2% correctly-abstained).

License

Apache-2.0 (see LICENSE). This is the open-source client surface. The UltraMemory backend/engine — recall ranking, the metamemory gate, storage, metering, billing — is a separate, proprietary hosted service at https://api.ultramemory.us.