cosmos-mcp

One exocortex. Every agent.
_{MCP server for your Cosmos graph.}

---

Every AI you use is building its own private graph of you. Claude has one. ChatGPT has one. Cursor has one. None of them talk to each other, and none of them are yours.

Cosmos inverts that. Your knowledge graph lives in one place, and any MCP-capable client (Claude Code, Claude Desktop, Cursor, Codex, Zed, Continue) reads and writes to the same one. When an agent notices something durable about you, it lands in the graph. When you switch tools, the graph follows. The user, not the platform, owns the integration layer.

The thing you carry is a .polarity file. Yours.

Install

npx -y @polarity-lab/cosmos-mcp init

Opens your browser. Sign in at cosmos.polarity-lab.com, approve a per-user key, and the token lands at ~/.config/cosmos-mcp/token (0600). Then point any MCP client at it:

{
  "mcpServers": {
    "cosmos": {
      "command": "npx",
      "args": ["-y", "@polarity-lab/cosmos-mcp"]
    }
  }
}

That config drops into ~/Library/Application Support/Claude/claude_desktop_config.json for Claude Desktop, your .cursor/mcp.json for Cursor, the equivalent for whichever client.

What you get

Eleven tools, four read, seven write.

Read

Tool	Calls	What it returns
polarity_whoami	GET /api/polarity/whoami	Bound user + scopes. Cheap probe.
polarity_export	POST /api/polarity/export	Full personal graph as polarity/v1 JSON.
polarity_get_graph	GET /api/polarity	Graph view, scoped by entity (user, cosmos, polarity).
polarity_ask	POST /api/polarity/ask	NL question synthesized over the graph.

Write

Tool	Calls	What it does
polarity_observe	POST /api/polarity/observe	Freeform observation. Cosmos extracts.
polarity_record_event	POST /api/polarity/observe (kind=event)	Something happened at a point in time.
polarity_record_preference	POST /api/polarity/observe (kind=preference)	A like, dislike, working-style rule.
polarity_capture_turn	POST /api/polarity/capture-turn	Hand a whole user/assistant exchange to cosmos. Pulls every durable observation in one call. Prefer over multiple polarity_observe calls.
polarity_dump	POST /api/polarity/dump	Location-anchored short message.
polarity_checkin	POST /api/polarity/checkin	Check-in at a waypoint. Triggers co-presence detection.
polarity_declare	POST /api/polarity/declare	Declare future presence at a waypoint.

Sources

The MCP server is one way to write to the graph. Cosmos accepts source pages from anywhere you keep notes, and the MCP read tools see all of it through the same view.

Source	How it connects	What lands
Notion	OAuth at cosmos.polarity-lab.com/connectors. Pick the pages and databases you want shared.	Each Notion page becomes a source_page node, keyed by Notion id, kept fresh by a daily sync.
Obsidian	Community plugin: polarity-lab/obsidian-cosmos. Paste your pmk_ key, point at your vault.	Each note becomes a source_page node keyed by vault-relative path. Tags and wikilinks resolve into edges.
MCP clients	This package.	Observations, events, preferences, location dumps, check-ins, declarations.
Direct API	POST /api/polarity/observe with your key.	Anything you can express as an observation.

Unchanged pages are skipped server-side, so re-syncing a quiet vault or stable Notion workspace costs almost nothing.

Configuration

Env var	Default	When you set it
COSMOS_URL	https://cosmos.polarity-lab.com	Pointing at your own cosmos.
COSMOS_MCP_KEY	(from token file)	pmk_... per-user key. Overrides cache.
COSMOS_USER_ID	(from token file)	Polarity user id.
COSMOS_SYSTEM_KEY	(unset)	Single-tenant mode. Sends X-System-Key instead of X-MCP-Key. Requires COSMOS_USER_ID. For self-hosters or testing before per-user keys are deployed.

Self-hosting

The cosmos backend is open. Run taiscoding/cosmos on your own Cloudflare account, mint a key against your instance, set COSMOS_URL to your domain. The graph stays on your D1. The .polarity export still works.

The pitch in three lines

Your AI tools each know fragments of you. They are not allowed to share. Cosmos is the layer that lets them. You hold the key. The graph is portable. When you leave, you take the understanding with you.

License

MIT.