Glossary
MCP (Model Context Protocol)
An open standard that lets LLMs call typed, schema-described tools over a single endpoint.
The Model Context Protocol (MCP) is an open standard, originally proposed by Anthropic, for letting LLMs call typed tools over a single endpoint. An MCP server publishes a list of tools — each with a JSON Schema for inputs and outputs — and the LLM picks which tool to call based on the user’s request.
Helix exposes its identity primitives as MCP tools: read-inbox, draft-reply, schedule, request-approval, and so on. Any MCP-aware client (Claude Desktop, Cursor, ChatGPT custom GPTs, n8n) can drive a Helix agent without bespoke glue code. The MCP shim is open-source on GitHub at `@nylas/helix-mcp-server`.
MCP is not a substitute for REST or webhooks; it is a complement. Helix exposes all three. The MCP endpoint is the easiest way to drive Helix from a chat client; the REST API is the right surface for server-to-server integrations.
Related terms
In product