[Server] add a reference handler setter to server builder#265
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simonchrz wants to merge 5 commits intomodelcontextprotocol:mainfrom
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[Server] add a reference handler setter to server builder#265simonchrz wants to merge 5 commits intomodelcontextprotocol:mainfrom
simonchrz wants to merge 5 commits intomodelcontextprotocol:mainfrom
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Allow consumers to provide a custom ReferenceHandlerInterface implementation (e.g. a security-aware decorator) instead of always using the default ReferenceHandler.
- Fluent API returns builder instance - build() succeeds with and without custom handler - Integration test verifies custom handler intercepts tool calls
simonchrz
requested review from
CodeWithKyrian,
Nyholm and
chr-hertel
as code owners
chr-hertel
requested changes
Mar 11, 2026
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Thanks @simonchrz - just one minor comment.
edit: plus
- pipeline failure looks real
- can you please add a changelog entry for 0.5.0 here
tests/Unit/Server/BuilderTest.php
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| $requestHandlers = (new \ReflectionClass($protocol))->getProperty('requestHandlers')->getValue($protocol); | ||
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| foreach ($requestHandlers as $handler) { | ||
| if ($handler instanceof \Mcp\Server\Handler\Request\CallToolHandler) { |
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please use imports for the FQCNs instead of fully inline
Suggested change
| if ($handler instanceof \Mcp\Server\Handler\Request\CallToolHandler) { | |
| if ($handler instanceof CallToolHandler) { |
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Added a setReferenceHandler method to Mcp\Server\Builder.
Motivation and Context
The MCP SDK's Builder hardcodes new ReferenceHandler($container) internally — there's no way to customize how tool/resource/prompt handlers are invoked. This prevents consumers from adding cross-cutting concerns like authorization checks before tool execution.
We want to decorate the ReferenceHandler with a SecurityReferenceHandler that reads Symfony's #[IsGranted] attribute from tool methods and checks permissions via the AuthorizationCheckerInterface before delegating to the actual handler. Without setReferenceHandler(), the only alternatives are fragile workarounds (event listener hacks, replacing internal request handlers via reflection, or duplicating authorization logic inside every tool method).
How Has This Been Tested?
I've added Mcp\Tests\Unit\Server\BuilderTest and tested it manually agains librechat mcp client.
Breaking Changes
no, it's optional
Types of changes
Checklist