c9d36b04bf
Three pages carried names the 2026-07-28 specification does not use: "Multi-Round-Trip Results" for the pattern the specification titles Multi Round-Trip Requests (MRTR) and serves at basic/patterns/mrtr - the results are the `InputRequiredResult` wire type, not the feature - plus "Completions" for the utility the specification titles Completion, and "Notification Subscriptions" for the pattern it titles Subscriptions. Retitle the three pages to the specification's names, move them to /server/mrtr/ and /client/mrtr/, /server/completion/, and /server/subscriptions/ following the specification's slugs, update every internal reference, and keep the URLs published with v1.3.0 working via jekyll-redirect-from. The Discovery page keeps its title but moves from /server/discovery/ to /server/discover/, matching the specification's slug and the `server/discover` RPC, with its published URL redirected the same way.
54 lines
1.7 KiB
Markdown
54 lines
1.7 KiB
Markdown
---
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layout: default
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title: Completion
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nav_order: 16
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redirect_from:
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- /server/completions/
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---
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# Completion
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MCP spec includes [Completions](https://modelcontextprotocol.io/specification/latest/server/utilities/completion),
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which enable servers to provide autocompletion suggestions for prompt arguments and resource URIs.
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To enable completions, declare the `completions` capability and register a handler:
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```ruby
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server = MCP::Server.new(
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name: "my_server",
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prompts: [CodeReviewPrompt],
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resource_templates: [FileTemplate],
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capabilities: { completions: {} },
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)
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server.completion_handler do |params|
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ref = params[:ref]
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argument = params[:argument]
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value = argument[:value]
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case ref[:type]
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when "ref/prompt"
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values = case argument[:name]
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when "language"
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["python", "pytorch", "pyside"].select { |v| v.start_with?(value) }
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else
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[]
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end
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{ completion: { values: values, hasMore: false } }
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when "ref/resource"
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{ completion: { values: [], hasMore: false } }
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end
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end
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```
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The handler receives a `params` hash with:
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- `ref` - The reference (`{ type: "ref/prompt", name: "..." }` or `{ type: "ref/resource", uri: "..." }`)
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- `argument` - The argument being completed (`{ name: "...", value: "..." }`)
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- `context` (optional) - Previously resolved arguments (`{ arguments: { ... } }`)
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The handler must return a hash with a `completion` key containing `values` (array of strings), and optionally `total` and `hasMore`.
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The SDK automatically enforces the 100-item limit per the MCP specification.
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The server validates that the referenced prompt, resource, or resource template is registered before calling the handler.
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Requests for unknown references return an error.
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