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

# ModelSelector

```ts theme={null}
type ModelSelector = string | ((prefs) => string);
```

Defined in: [client/sampling/types.ts:10](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/client/sampling/types.ts#L10)

Resolve a concrete model name from the server's modelPreferences.
A plain string always uses that model; a function inspects the preferences.