MCP servers

Helix speaks the Model Context Protocol (MCP). It ships no MCP server of its own: the servers you configure are the ones it uses, and their tools reach the model directly, next to Helix’s own tools.

Add a server

List your servers in an mcp.json file, in the mcpServers shape other MCP clients use:

File	Applies to
`~/.mutagent/agent/mcp.json`	Every Helix session on your machine.
`.pi/mcp.json` in your project	Sessions in that project, once you trust it.

mcp.json

{
  "mcpServers": {
    "filesystem": { "command": "npx", "args": ["-y", "@modelcontextprotocol/server-filesystem", "."] },
    "docs": { "url": "https://example.com/mcp", "headers": { "Authorization": "Bearer ${DOCS_TOKEN}" } }
  }
}

A local server runs from command and args; a remote one is reached at url. The next Helix session loads them.

How the model sees the tools

Each tool is offered to the model as mcp__<server>__<tool>, for example mcp__docs__search. The model calls it like any other tool.

Leave a server’s exposure field out, or set it to "direct". A server set to "codemode" or "deferred" has no tools Helix can call, and Helix warns about it.

Where MCP tools are available

	MCP tools
`helix` and `helix agent`	Offered to the model directly.
`helix --prime`	Called from code: a cell can search your MCP tools, read a tool’s parameters and call it. See Prime.
Sub-agents	Not available. A sub-agent works with Helix’s own tools.

Project context

The other thing every session loads from your project: AGENTS.md / CLAUDE.md.

Get started

Run it

Lifecycle

Features

Helix Cloud

Reference

Add a server

How the model sees the tools

Where MCP tools are available

Project context

​Add a server

​How the model sees the tools

​Where MCP tools are available

Project context

Add a server

How the model sees the tools

Where MCP tools are available