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

# response_limiting

# `fastmcp.server.middleware.response_limiting`

Response limiting middleware for controlling tool response sizes.

## Classes

### `ResponseLimitingMiddleware` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/middleware/response_limiting.py#L20" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Middleware that limits the response size of tool calls.

Intercepts tool call responses and enforces size limits. If a response
exceeds the limit, it extracts text content, truncates it, and returns
a single TextContent block.

**Methods:**

#### `on_call_tool` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/middleware/response_limiting.py#L93" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_call_tool(self, context: MiddlewareContext[mt.CallToolRequestParams], call_next: CallNext[mt.CallToolRequestParams, ToolResult]) -> ToolResult
```

Intercept tool calls and limit response size.