# Source: https://gofastmcp.com/python-sdk/fastmcp-server-middleware-middleware.md

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

# middleware

# `fastmcp.server.middleware.middleware`

## Functions

### `make_middleware_wrapper` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L66" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
make_middleware_wrapper(middleware: Middleware, call_next: CallNext[T, R]) -> CallNext[T, R]
```

Create a wrapper that applies a single middleware to a context. The
closure bakes in the middleware and call\_next function, so it can be
passed to other functions that expect a call\_next function.

## Classes

### `CallNext` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L42" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

### `MiddlewareContext` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L47" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Unified context for all middleware operations.

**Methods:**

#### `copy` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L62" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
copy(self, **kwargs: Any) -> MiddlewareContext[T]
```

### `Middleware` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L79" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Base class for FastMCP middleware with dispatching hooks.

**Methods:**

#### `on_message` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L128" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_message(self, context: MiddlewareContext[Any], call_next: CallNext[Any, Any]) -> Any
```

#### `on_request` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L135" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

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

#### `on_notification` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L142" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

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

#### `on_initialize` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L149" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_initialize(self, context: MiddlewareContext[mt.InitializeRequest], call_next: CallNext[mt.InitializeRequest, mt.InitializeResult | None]) -> mt.InitializeResult | None
```

#### `on_call_tool` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L156" 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
```

#### `on_read_resource` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L163" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

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

#### `on_get_prompt` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L170" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

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

#### `on_list_tools` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L177" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_list_tools(self, context: MiddlewareContext[mt.ListToolsRequest], call_next: CallNext[mt.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool]
```

#### `on_list_resources` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L184" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_list_resources(self, context: MiddlewareContext[mt.ListResourcesRequest], call_next: CallNext[mt.ListResourcesRequest, Sequence[Resource]]) -> Sequence[Resource]
```

#### `on_list_resource_templates` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L191" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_list_resource_templates(self, context: MiddlewareContext[mt.ListResourceTemplatesRequest], call_next: CallNext[mt.ListResourceTemplatesRequest, Sequence[ResourceTemplate]]) -> Sequence[ResourceTemplate]
```

#### `on_list_prompts` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/middleware.py#L200" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python  theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_list_prompts(self, context: MiddlewareContext[mt.ListPromptsRequest], call_next: CallNext[mt.ListPromptsRequest, Sequence[Prompt]]) -> Sequence[Prompt]
```