> ## Documentation Index
> Fetch the complete documentation index at: https://muxaiio.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP Servers

> How agents access external tools and data through the Model Context Protocol.

## What is MCP?

MCP (Model Context Protocol) is how agents access external tools. An MCP server exposes a set of tools (functions) that the agent can call during a run. muxAI manages which MCP servers each agent can access.

## Built-in servers

muxAI ships with several MCP servers out of the box:

| Server            | Tools                                          | Purpose                                                                            |
| ----------------- | ---------------------------------------------- | ---------------------------------------------------------------------------------- |
| **news-analyst**  | RSS feeds, CoinMarketCap news                  | Fetch and analyze crypto news                                                      |
| **chart-analyst** | Chart image analysis                           | Analyze trading charts from URLs                                                   |
| **orchestrator**  | `run_team`, `ask_reporter`, `get_my_decisions` | Coordinate team members (lead agents only) and recall past decisions with outcomes |
| **contractor**    | `ask_contractor`, `list_contractors`           | Consult external LLM contractors                                                   |
| **wallet**        | `wallet_address`, `wallet_fetch`               | Agent wallet access and x402 payments                                              |
| **docs**          | `search_docs`, `get_doc_page`                  | Search and read muxAI platform documentation                                       |

Built-in servers are registered in `config/mcp-registry.json` and automatically available when an agent uses **Built-in** MCP mode.

## Custom servers

Add your own MCP servers through the **MCP Servers** page. Two transport types are supported:

<Columns cols={2}>
  <Card title="stdio" icon="terminal">
    Runs as a local process. You provide the command and arguments. The agent communicates over stdin/stdout.

    Example: a Python script that wraps a proprietary API.
  </Card>

  <Card title="HTTP" icon="globe">
    Connects to a remote server via URL. Optionally include authentication headers.

    Example: an MCP server running on another machine or cloud service.
  </Card>
</Columns>

### Adding a custom server

<Tabs>
  <Tab title="Paste JSON" icon="paste">
    Paste a standard MCP config JSON block. muxAI parses it, shows a preview, and imports all servers at once.

    ```json theme={null}
    {
      "mcpServers": {
        "my-server": {
          "command": "node",
          "args": ["path/to/server.js"]
        }
      }
    }
    ```
  </Tab>

  <Tab title="Manual" icon="pen">
    Fill in the fields: name, command/URL, arguments, optional headers, and description.
  </Tab>
</Tabs>

## MCP modes

Each agent is configured with one of two MCP modes:

| Mode                   | Behavior                                                                                                                                                |
| ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Built-in** (default) | Agent gets only the built-in servers plus any custom servers from the database. Uses `--mcp-config` and `--strict-mcp-config` flags for full isolation. |
| **Global**             | Agent inherits MCP servers from your global Claude CLI config (`~/.claude`). No isolation flags.                                                        |

Built-in mode is recommended. It prevents global MCP servers from leaking into agent runs and ensures reproducible behavior.

## How it works at runtime

When an agent runs in Built-in mode, muxAI:

1. Reads the built-in registry (`config/mcp-registry.json`)
2. Loads custom servers from the database
3. Merges them into a single MCP config JSON
4. Passes it to the Claude CLI via `--mcp-config <path> --strict-mcp-config`

The agent can only call tools from servers in that config. Nothing else.

## Guides

<CardGroup cols={2}>
  <Card title="Add a Custom MCP Server" icon="plus" href="/guides/add-custom-mcp-server">
    Connect an existing MCP server through the portal UI. No code changes required.
  </Card>

  <Card title="Build a Built-in MCP Server" icon="hammer" href="/guides/build-mcp-server">
    Create a new MCP server package that ships with your muxAI installation.
  </Card>
</CardGroup>