> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tai42.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Bring an MCP server

> Mount an external MCP server's tools.

Mount an existing external MCP server so its tools appear in your running server.

The runtime mounts other MCP servers and re-presents their tools as its own. You declare each server in the manifest's `mcp` section; the runtime probes it at startup and binds its tools alongside your local ones.

## Declare a server in the manifest

Each `mcp` entry names one server. Set exactly one transport per entry — the runtime infers the transport from whichever field you set:

* `url` for a remote HTTP or SSE server (with optional `headers`),
* `uds` for a Unix domain socket,
* `command` (plus `args` / `env`) for a stdio server the runtime launches.

```yaml manifest.yml theme={null}
mcp:
  - title: example-http
    config:
      url: https://mcp.example.com/mcp
      headers: {}
  - title: example-stdio
    config:
      command: uvx
      args: [some-mcp-server]
      env: {}
```

Use `include` / `exclude` on an entry to expose only a subset of the mounted server's tools.

## Inspect and reload

<Steps>
  <Step title="Check binding status">
    Snapshot the live MCP binding state — which servers attached and which were skipped by a failed viability probe.

    ```bash theme={null}
    tai mcp status
    ```
  </Step>

  <Step title="Replace the set at runtime">
    Write the full replacement `mcp` list to a JSON file, then apply it. This hot-reloads the section without restarting the server.

    ```bash theme={null}
    tai mcp set --file mcp.json
    ```
  </Step>

  <Step title="Reload one server">
    Re-probe a single server by its manifest title and re-attach it if it is viable.

    ```bash theme={null}
    tai mcp reload example-http
    ```
  </Step>
</Steps>

<Note>
  A server that fails its viability probe is skipped, not fatal — the rest of the manifest still loads. Inspect skipped servers under `tai mcp status`.
</Note>

## See also

* [Transports](/concepts/transports) — the HTTP, SSE, stdio, and UDS paths a mounted server can use.
* [The manifest](/concepts/manifest) — the `mcp` section and its selection fields.
* [Live operations](/concepts/live-operations) — hot-reload and deregister at runtime.
* [CLI reference](/reference/cli) — the full `tai mcp` surface.