Support completion/complete per MCP specification#289
Merged
koic merged 1 commit intomodelcontextprotocol:mainfrom Apr 3, 2026
Merged
Support completion/complete per MCP specification#289koic merged 1 commit intomodelcontextprotocol:mainfrom
completion/complete per MCP specification#289koic merged 1 commit intomodelcontextprotocol:mainfrom
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## Motivation and Context The MCP specification defines `completion/complete` for providing autocompletion suggestions for prompt arguments and resource template URIs. The Ruby SDK previously had only a no-op handler that returned empty results, with no way for users to define custom completion logic. This aligns the Ruby SDK with the Python and TypeScript SDKs, both of which support user-defined completion handlers. ## How Has This Been Tested? Server tests cover: default handler, custom handler for `ref/prompt` and `ref/resource`, context argument passing, 100-item truncation, and error responses for nonexistent prompts, nonexistent resource templates, and invalid ref types. Client tests cover: request structure, context parameter inclusion, and fallback when result is missing. ## Breaking Changes None. The existing default no-op handler behavior is preserved. The `completion_handler` method is purely additive. The only behavioral change is that `completion/complete` requests now validate that the referenced prompt or resource template exists before calling the handler, returning an `invalid_params` error for unknown references.
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Motivation and Context
The MCP specification defines
completion/completefor providing autocompletion suggestions for prompt arguments and resource template URIs. The Ruby SDK previously had only a no-op handler that returned empty results, with no way for users to define custom completion logic.This aligns the Ruby SDK with the Python and TypeScript SDKs, both of which support user-defined completion handlers.
How Has This Been Tested?
Server tests cover: default handler, custom handler for
ref/promptandref/resource, context argument passing, 100-item truncation, and error responses for nonexistent prompts, nonexistent resource templates, and invalid ref types.Client tests cover: request structure, context parameter inclusion, and fallback when result is missing.
Breaking Changes
None. The existing default no-op handler behavior is preserved. The
completion_handlermethod is purely additive. The only behavioral change is thatcompletion/completerequests now validate that the referenced prompt or resource template exists before calling the handler, returning aninvalid_paramserror for unknown references.Types of changes
Checklist