> ## Documentation Index
> Fetch the complete documentation index at: https://gofastmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.
# __init__
# `fastmcp.server.transforms`
Transform system for component transformations.
Transforms modify components (tools, resources, prompts). List operations use a pure
function pattern where transforms receive sequences and return transformed sequences.
Get operations use a middleware pattern with `call_next` to chain lookups.
Unlike middleware (which operates on requests), transforms are observable by the
system for task registration, tag filtering, and component introspection.
Example:
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
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.
List operations use a pure function pattern: transforms receive sequences
and return transformed sequences. Get operations use a middleware pattern
with `call_next` to chain lookups.
**Methods:**
#### `list_tools`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
list_tools(self, tools: Sequence[Tool]) -> Sequence[Tool]
```
List tools with transformation applied.
**Args:**
* `tools`: Sequence of tools to transform.
**Returns:**
* Transformed sequence of tools.
#### `get_tool`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
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 theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
list_resources(self, resources: Sequence[Resource]) -> Sequence[Resource]
```
List resources with transformation applied.
**Args:**
* `resources`: Sequence of resources to transform.
**Returns:**
* Transformed sequence of resources.
#### `get_resource`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
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 theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
list_resource_templates(self, templates: Sequence[ResourceTemplate]) -> Sequence[ResourceTemplate]
```
List resource templates with transformation applied.
**Args:**
* `templates`: Sequence of resource templates to transform.
**Returns:**
* Transformed sequence of resource templates.
#### `get_resource_template`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
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 theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
list_prompts(self, prompts: Sequence[Prompt]) -> Sequence[Prompt]
```
List prompts with transformation applied.
**Args:**
* `prompts`: Sequence of prompts to transform.
**Returns:**
* Transformed sequence of prompts.
#### `get_prompt`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
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.