---
title: __init__
sidebarTitle: __init__
---
# `fastmcp.server.transforms`
Transform system for component transformations.
Transforms modify components (tools, resources, prompts) using a middleware pattern.
Each transform wraps the next in the chain via `call_next`, allowing transforms to
intercept, modify, or replace component queries.
Unlike middleware (which operates on requests), transforms are observable by the
system for task registration, tag filtering, and component introspection.
Example:
```python
from fastmcp import FastMCP
from fastmcp.server.transforms import Namespace
server = FastMCP("Server")
mount = server.mount(other_server)
mount.add_transform(Namespace("api")) # Tools become api_toolname
```
## Classes
### `GetToolNext`
Protocol for get_tool call_next functions.
### `GetResourceNext`
Protocol for get_resource call_next functions.
### `GetResourceTemplateNext`
Protocol for get_resource_template call_next functions.
### `GetPromptNext`
Protocol for get_prompt call_next functions.
### `Transform`
Base class for component transformations.
Transforms use a middleware pattern with `call_next` to chain operations.
Each transform can intercept, modify, or pass through component queries.
For list operations, call `call_next()` to get components from downstream,
then transform the result. For get operations, optionally transform the
name/uri before calling `call_next`, then transform the result.
**Methods:**
#### `list_tools`
```python
list_tools(self, call_next: ListToolsNext) -> Sequence[Tool]
```
List tools with transformation applied.
**Args:**
- `call_next`: Callable to get tools from downstream transforms/provider.
**Returns:**
- Transformed sequence of tools.
#### `get_tool`
```python
get_tool(self, name: str, call_next: GetToolNext) -> Tool | None
```
Get a tool by name.
**Args:**
- `name`: The requested tool name (may be transformed).
- `call_next`: Callable to get tool from downstream.
- `version`: Optional version filter to apply.
**Returns:**
- The tool if found, None otherwise.
#### `list_resources`
```python
list_resources(self, call_next: ListResourcesNext) -> Sequence[Resource]
```
List resources with transformation applied.
**Args:**
- `call_next`: Callable to get resources from downstream transforms/provider.
**Returns:**
- Transformed sequence of resources.
#### `get_resource`
```python
get_resource(self, uri: str, call_next: GetResourceNext) -> Resource | None
```
Get a resource by URI.
**Args:**
- `uri`: The requested resource URI (may be transformed).
- `call_next`: Callable to get resource from downstream.
- `version`: Optional version filter to apply.
**Returns:**
- The resource if found, None otherwise.
#### `list_resource_templates`
```python
list_resource_templates(self, call_next: ListResourceTemplatesNext) -> Sequence[ResourceTemplate]
```
List resource templates with transformation applied.
**Args:**
- `call_next`: Callable to get templates from downstream transforms/provider.
**Returns:**
- Transformed sequence of resource templates.
#### `get_resource_template`
```python
get_resource_template(self, uri: str, call_next: GetResourceTemplateNext) -> ResourceTemplate | None
```
Get a resource template by URI.
**Args:**
- `uri`: The requested template URI (may be transformed).
- `call_next`: Callable to get template from downstream.
- `version`: Optional version filter to apply.
**Returns:**
- The resource template if found, None otherwise.
#### `list_prompts`
```python
list_prompts(self, call_next: ListPromptsNext) -> Sequence[Prompt]
```
List prompts with transformation applied.
**Args:**
- `call_next`: Callable to get prompts from downstream transforms/provider.
**Returns:**
- Transformed sequence of prompts.
#### `get_prompt`
```python
get_prompt(self, name: str, call_next: GetPromptNext) -> Prompt | None
```
Get a prompt by name.
**Args:**
- `name`: The requested prompt name (may be transformed).
- `call_next`: Callable to get prompt from downstream.
- `version`: Optional version filter to apply.
**Returns:**
- The prompt if found, None otherwise.