* Consolidate tool transformation logic into TransformingProvider
Tool transformations were previously scattered across LocalProvider,
ProxyProvider, and MCPConfig. This consolidates all transformation
logic into TransformingProvider via with_transforms(tool_transforms={...}).
- Add tool_transforms parameter to TransformingProvider
- Add tool_transforms to Provider.with_transforms()
- Remove transformation storage from LocalProvider and ProxyProvider
- Remove add_tool_transformation() and remove_tool_transformation() from FastMCP
- Add tool_transforms parameter to factory methods (from_openapi, from_fastapi, create_proxy)
- Update tests to use new patterns
* Fix: reject tool lookups by pre-transform name
* Add collision validation for tool_transforms and fix docstring examples
- Validate duplicate target names in tool_transforms raise ValueError
- Fix docstring examples to use arguments/ArgTransformConfig (not args/ArgTransform)
- Add test for collision validation
* Add server-level tool transform APIs and fix task registration
- Add AggregateProvider to present multiple providers as one
- Add _get_root_provider() to apply server-level transforms uniformly
- Fix _docket_lifespan to use root provider (ensures renamed tools
register with correct keys for background execution)
- Add tool_transforms kwarg to __init__ (non-deprecated)
- Add add_tool_transform(), remove_tool_transform(), tool_transforms property
- Deprecate old API names (tool_transformations, add_tool_transformation, etc.)
- Update tests to use new API
* Add graceful degradation for provider errors in AggregateProvider
* Match original behavior: parallel queries with DEBUG logging
* Refactor transforms to middleware-style call_next pattern
Replaces the ad-hoc transformation system with a unified Transform
abstraction using the same call_next pattern as server middleware.
Key changes:
- New src/fastmcp/server/transforms/ module with Transform base class
- Namespace, ToolTransform, Visibility all implement the same interface
- Transforms compose via functools.partial chain building
- Visibility is now just the first transform in provider._transforms
- Server-level transforms apply after provider aggregation
- Task registration now applies full transform chain
Removes TransformingProvider, _BoundTransform, ComponentSource protocol.
User-facing API unchanged: mount(), add_transform(), enable/disable all
work as before.
* Add comprehensive transforms and visibility documentation
New docs/servers/providers/transforms.mdx covering:
- Mental model for middleware-style transform pattern
- Built-in transforms (Namespace, ToolTransform)
- Server vs provider-level transforms and ordering
- Tool modification (immediate vs deferred)
- Custom transform creation
New docs/servers/visibility.mdx covering:
- Enable/disable API for runtime visibility control
- Keys and tags for targeting components
- Allowlist mode with only=True
- Server vs provider visibility layering
Updates existing docs to reference new pages and simplifies
redundant content. Visibility is documented as a user feature,
not as an implementation detail.
* Restructure transforms docs and delete tool-transformation pattern
* Cleanup: simplify get_tasks and remove unused Provider.get_component
* Update loq
* Update loq limits and add loq note to AGENTS.md
* Deprecate add_tool_transformation and tool_transformations param
* Address PR review feedback: remove redundant imports, fix path reference
* Add missing imports to code examples in v3-features.mdx
* feat: handle error from the initialize middleware
In some situation, the initialize middleware can check the status of the
server and decide to raise an error.
Example use case: in a FastMCPProxy, an initialization middleware
overrides the on_initialize method and connect to the underlying proxied
client. When client respond with error, I want to pass this error to the
client.
* docs update
* test: use McpError assertions now that exception propagation is fixed
- Update tests to catch McpError specifically instead of generic Exception
- Remove commented-out code in low_level.py
---------
Co-authored-by: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
The on_initialize hook (2.13.0) runs before the MCP session is established, causing request_context
to be unavailable. Changed request_context to return None instead of raising, allowing middleware to
check availability and use HTTP helpers when needed. Updated docs to guide this pattern.
Closes#2393
* Add compatibility tools contrib module
Implements four standalone tools that expose resources and prompts
as callable tools for clients that only support the tools capability.
Features:
- list_resources: List all available resources
- get_resource: Read a resource by URI
- list_prompts: List all available prompts
- get_prompt: Get a prompt with optional arguments
The tools use Context to access the server instance and can be easily
added to any FastMCP server using the add_compatibility_tools helper
or by adding individual tool instances directly.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: William Easton <strawgate@users.noreply.github.com>
* Simplify compatibility tools to return raw MCP protocol objects
Return raw MCP protocol objects (ListResourcesResult, ReadResourceResult,
ListPromptsResult, GetPromptResult) instead of custom dictionaries. This
makes the tools simpler and more predictable by directly exposing what
the client methods return.
Co-authored-by: William Easton <strawgate@users.noreply.github.com>
* Add tool injection middleware
* cleanup contrib module
* More clean-up
* Clean up tool injection middleware.
* Update src/fastmcp/server/middleware/tool_injection.py
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
* Add tool injection docs
* Small cleanup of prompt middleware
* PR Feedback
* Fix tool injection tests
---------
Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: William Easton <strawgate@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
* Catch more openapi changes
* Simplify middleware list operations to use lists directly
- Updated middleware signatures to work with list[Tool], list[Resource], etc instead of wrapper objects
- Removed unnecessary ListToolsResult, ListResourcesResult wrapper types
- Updated documentation to show simpler list-based filtering pattern
- Added tests for list-based middleware filtering
Closes#1121🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
---------
Co-authored-by: Claude <noreply@anthropic.com>
Implements timing, logging, rate limiting, and error handling middleware to showcase
FastMCP's middleware capabilities as a headline feature. Each middleware includes:
- Production-ready implementations with full configurability
- Comprehensive unit and integration tests with real FastMCP servers
- Updated documentation with teaching examples and production usage patterns
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
