> ## 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.

# RunOptions

Defined in: [server/FastMCP.ts:172](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L172)

## Properties

### host?

```ts theme={null}
optional host?: string;
```

Defined in: [server/FastMCP.ts:175](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L175)

***

### path?

```ts theme={null}
optional path?: string;
```

Defined in: [server/FastMCP.ts:176](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L176)

***

### port?

```ts theme={null}
optional port?: number;
```

Defined in: [server/FastMCP.ts:174](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L174)

***

### stateless?

```ts theme={null}
optional stateless?: boolean;
```

Defined in: [server/FastMCP.ts:188](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L188)

Serve the legacy (2025-era) HTTP transport statelessly: a fresh server and
transport per request, no session registry, incoming `mcp-session-id`
ignored, and no session id issued. Use this behind a load balancer or on
serverless compute where consecutive requests reach different instances.

Falls back to the `FASTMCP_STATELESS_HTTP` environment variable, then to
`false`. A valid value is ignored for the stdio transport, but a malformed
one still aborts stdio startup, deliberately. The modern (2026-07-28) era
is already stateless and is unaffected.

***

### stdin?

```ts theme={null}
optional stdin?: Readable;
```

Defined in: [server/FastMCP.ts:190](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L190)

Custom stdin stream for the stdio transport. Defaults to process.stdin.

***

### stdout?

```ts theme={null}
optional stdout?: Writable;
```

Defined in: [server/FastMCP.ts:192](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L192)

Custom stdout stream for the stdio transport. Defaults to process.stdout.

***

### transport?

```ts theme={null}
optional transport?: "stdio" | "http";
```

Defined in: [server/FastMCP.ts:173](https://github.com/PrefectHQ/fastmcp-ts/blob/8976c37f79efa6b87809b884f29a1f235a8c4ad1/src/server/FastMCP.ts#L173)