Open Context runs a hosted MCP server. MCP — the Model Context Protocol — is the standard that lets an AI assistant call out to an outside service mid-conversation. Connect Open Context and your assistant gains 21 tools for reading and saving your profile, Library, and Spaces.
The practical effect: your context lives in one place instead of being re-explained at the start of every chat. Move from Claude to ChatGPT to Cursor and the same Library is there.
Signing in
On the catalog paths — Claude and ChatGPT — you sign in through your browser. The assistant sends you to opnctx.ai, you approve access once, and it stores the tokens from there. No API key to copy, no config file to edit.
The MCP endpoint is https://mcp.opnctx.ai. That’s the root of the MCP host, not a REST API path.
Clients that support discovery configure themselves from that URL alone. Open Context publishes authorization server metadata at the standard /.well-known endpoints and accepts dynamic client registration, so there’s usually nothing else to supply. Authentication is OAuth 2.0 Authorization Code with PKCE.
The Chrome extension is separate and does use an API key. Connecting an assistant doesn’t require one — see Chrome extension if you’re setting that up too.
Which clients
From a catalog — search, click, approve. Nothing to paste.
- Claude — Settings → Connectors → Add → Browse connectors → OpenContext. See Claude.
- ChatGPT — Plugins → search Open Context → Install plugin. See ChatGPT.
Both listings are published by FOUND Studios LLC.
By URL — point the client at https://mcp.opnctx.ai.
- Cursor — See Cursor for config file paths and scopes.
- Anything else MCP-capable — See Any MCP client, which also covers the API key path for headless clients that can’t open a browser.
When it stops working
Most failures are expired or revoked consent. Disconnect the connector, reconnect it, and complete sign-in again — that reruns the whole flow.
If tools don’t appear at all after connecting, fully quit and reopen the client; a window reload often isn’t enough for it to register a new MCP server. Any MCP client has the longer troubleshooting list.