fastmcp/docs/python-sdk/fastmcp-server-transforms-visibility.mdx

---
title: visibility
sidebarTitle: visibility
---

# `fastmcp.server.transforms.visibility`


Visibility transform for filtering components based on enable/disable settings.

This module provides the `Visibility` class which manages component visibility
with blocklist and allowlist support. Components can be hidden by key or tag,
and the visibility state is mutable - changes take effect on subsequent queries.


## Classes

### `Visibility` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L43" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Filters components based on visibility settings.

Manages blocklist and allowlist logic for controlling component visibility.
Both servers and providers use this class. Visibility is hierarchical: if a
component is hidden at any level (provider or server), it's hidden to the client.

Filtering logic (blocklist wins over allowlist):
1. If component key is in _disabled_keys → HIDDEN
2. If any component tag is in _disabled_tags → HIDDEN
3. If _default_enabled is False and component not in allowlist → HIDDEN
4. Otherwise → VISIBLE

The `only=True` flag on enable() switches to allowlist mode:
- Sets _default_enabled = False
- Clears existing allowlists
- Adds specified keys/tags to allowlist


**Methods:**

#### `disable` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L120" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
disable(self) -> None
```

Add to blocklist (hide components).

**Args:**
- `keys`: Component keys to hide (e.g., "tool\:my_tool@", "resource\:file\://x@")
- `tags`: Tags to hide - any component with these tags will be hidden


#### `enable` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L148" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
enable(self) -> None
```

Remove from blocklist, or set allowlist with only=True.

**Args:**
- `keys`: Component keys to show
- `tags`: Tags to show
- `only`: If True, switches to allowlist mode - ONLY show these keys/tags.
This sets default visibility to False, clears existing allowlists,
and adds the specified keys/tags to the allowlist.


#### `reset` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L202" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
reset(self) -> None
```

Reset to default state (everything enabled, no filters).


#### `is_enabled` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L221" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
is_enabled(self, component: FastMCPComponent) -> bool
```

Check if component is enabled. Blocklist wins over allowlist.


#### `list_tools` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L241" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
list_tools(self, call_next: ListToolsNext) -> Sequence[Tool]
```

Filter tools by visibility.


#### `get_tool` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L246" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_tool(self, name: str, call_next: GetToolNext) -> Tool | None
```

Get tool if enabled, None otherwise.


#### `list_resources` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L259" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
list_resources(self, call_next: ListResourcesNext) -> Sequence[Resource]
```

Filter resources by visibility.


#### `get_resource` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L264" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_resource(self, uri: str, call_next: GetResourceNext) -> Resource | None
```

Get resource if enabled, None otherwise.


#### `list_resource_templates` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L281" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
list_resource_templates(self, call_next: ListResourceTemplatesNext) -> Sequence[ResourceTemplate]
```

Filter resource templates by visibility.


#### `get_resource_template` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L288" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_resource_template(self, uri: str, call_next: GetResourceTemplateNext) -> ResourceTemplate | None
```

Get resource template if enabled, None otherwise.


#### `list_prompts` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L305" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
list_prompts(self, call_next: ListPromptsNext) -> Sequence[Prompt]
```

Filter prompts by visibility.


#### `get_prompt` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/transforms/visibility.py#L310" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_prompt(self, name: str, call_next: GetPromptNext) -> Prompt | None
```

Get prompt if enabled, None otherwise.