> ## 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.

# The MCP-citizen surface

> MCP-native features and the FastMCP escape hatch.

A tai server is a first-class MCP citizen. The MCP-native features — output
schemas and structured content, elicitation, progress, sampling, completions, and
native tags — are all reachable, and anything the platform's facets do not wrap is
reachable through one escape hatch to the raw underlying FastMCP server.

## Built on FastMCP

The skeleton's server is a FastMCP server underneath. The platform layers its own
governance over it — [manifest](/concepts/manifest) gating, the extension registry's
validation, and the [access-control](/concepts/access-control) gate — and exposes
its features through typed facets. The MCP-native capabilities ride the FastMCP
foundation, so an MCP client gets structured content, progress, elicitation, and
the rest as it would from any MCP server.

The server's management tools are not hand-registered on this surface: they
project from the [operations layer](/concepts/live-operations), curated by
[`api_tools`](/concepts/manifest#the-api_tools-block). An `AuthzMiddleware`
installed on this FastMCP instance and on every [sub-MCP](/concepts/private-tool-sets)
mount authorizes each projected-operation dispatch before the tool runs.

## The `app.fastmcp` escape hatch

For anything the facets do not wrap, the app exposes the raw FastMCP instance
directly:

```python theme={null}
from tai42_skeleton.app.instance import app

raw = app.fastmcp   # the raw, ungoverned FastMCP server
```

Reach here for what the facets deliberately leave to FastMCP — prompts, resources,
`add_middleware`, sampling, elicit-handlers, completions, server metadata such as
`name`/`version`/`auth`, and the process-global `fastmcp.settings`.

<Warning>
  Anything registered **through** `app.fastmcp` skips the platform's governance:
  manifest gating, the extension registry's validation, and the access-control gate.
  Prefer the facets; use the escape hatch only for what they do not cover. It is named
  `fastmcp` (not `mcp`) so it does not read as the [sub-MCP](/concepts/private-tool-sets)
  namespace, `app.sub_app`.
</Warning>

The accessor is intentionally not on the `TaiApp` contract protocol — the contract
stays FastMCP-free so an alternative implementation of the platform remains
possible, which makes this accessor skeleton-specific.

## FastMCP's own capabilities

The platform documents the escape hatch — what the `app.fastmcp` field is and what
it grants — not FastMCP's own API. For a deep dive into FastMCP's prompts,
resources, middleware, and the rest, see FastMCP's documentation at
[gofastmcp.com](https://gofastmcp.com).

See the [Python SDK reference](/reference/python-sdk/index) for the `app.fastmcp`
field and the platform's facets.