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fastmcp.server.transforms.visibility

Visibility transform for marking component visibility state. Each Visibility instance marks components via internal metadata. Multiple visibility transforms can be stacked - later transforms override earlier ones. Final filtering happens at the Provider level.

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Functions

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is_enabled

Check if component is enabled. Returns True if:
  • No visibility mark exists (default is enabled)
  • Visibility mark is True
Returns False if visibility mark is False. Args:
  • component: Component to check.
Returns:
  • True if component should be enabled/visible to clients.

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get_visibility_rules

Load visibility rule dicts from session state.

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save_visibility_rules

Save visibility rule dicts to session state and send notifications. Args:
  • context: The context to save rules for.
  • rules: The visibility rules to save.
  • components: Optional hint about which component types are affected. If None, sends notifications for all types (safe default). If provided, only sends notifications for specified types.

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create_visibility_transforms

Convert rule dicts to Visibility transforms.

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get_session_transforms

Get session-specific Visibility transforms from state store.

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enable_components

Enable components matching criteria for this session only. Session rules override global transforms. Rules accumulate - each call adds a new rule to the session. Later marks override earlier ones (Visibility transform semantics). Sends notifications to this session only: ToolListChangedNotification, ResourceListChangedNotification, and PromptListChangedNotification. Args:
  • context: The context for this session.
  • names: Component names or URIs to match.
  • keys: Component keys to match (e.g., ).
  • version: Component version spec to match.
  • tags: Tags to match (component must have at least one).
  • components: Component types to match (e.g., ).
  • match_all: If True, matches all components regardless of other criteria.

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disable_components

Disable components matching criteria for this session only. Session rules override global transforms. Rules accumulate - each call adds a new rule to the session. Later marks override earlier ones (Visibility transform semantics). Sends notifications to this session only: ToolListChangedNotification, ResourceListChangedNotification, and PromptListChangedNotification. Args:
  • context: The context for this session.
  • names: Component names or URIs to match.
  • keys: Component keys to match (e.g., ).
  • version: Component version spec to match.
  • tags: Tags to match (component must have at least one).
  • components: Component types to match (e.g., ).
  • match_all: If True, matches all components regardless of other criteria.

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reset_visibility

Clear all session visibility rules. Use this to reset session visibility back to global defaults. Sends notifications to this session only: ToolListChangedNotification, ResourceListChangedNotification, and PromptListChangedNotification. Args:
  • context: The context for this session.

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apply_session_transforms

Apply session-specific visibility transforms to components. This helper applies session-level enable/disable rules by marking components with their visibility state. Session transforms override global transforms due to mark-based semantics (later marks win). Args:
  • components: The components to apply session transforms to.
Returns:
  • The components with session transforms applied.

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Classes

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Visibility

Sets visibility state on matching components. Does NOT filter inline - just marks components with visibility state. Later transforms in the chain can override earlier marks. Final filtering happens at the Provider level after all transforms run. Methods:

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list_tools

Mark tools by visibility state.

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get_tool

Mark tool if found.

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list_resources

Mark resources by visibility state.

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get_resource

Mark resource if found.

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list_resource_templates

Mark resource templates by visibility state.

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get_resource_template

Mark resource template if found.

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list_prompts

Mark prompts by visibility state.

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get_prompt

Mark prompt if found.