feat: update mcp-core prompt to match spec, add mcp list/get to mcp-client by kalvinnchau · Pull Request #2 · modelcontextprotocol/rust-sdk

kalvinnchau · 2025-02-21T03:50:38Z

Update Prompt structs for align with MCP spec, and add list/get prompts to the mcp-client

Motivation and Context

Prompts description and arguments are optional fields, use optional in the structs
- similarly PromptArguments description and required are optional too
add list_prompts and get_prompt method to the McpClientTrait
add implementation of list_prompts and get_prompt to call prompts/list and prompts/get respectively
update stdio and sse clients to handle JsonRpcMessage::Error responses to send back to the user instead of doing nothing

How Has This Been Tested?

Tested locally with goose, and tested listing, and getting prompts and getting errors
Added implementation to crates/mcp-server/src/main.rs and usage of it in crates/mcp-client/examples/stdio_integration.rs

Breaking Changes

The Prompt struct API has changed description and arguments to be Option<T>
The PromptArgument struct API has changed description and required to be Option<T>
Router: get_prompt and list_prompt are now required to be implemented by types that want to impl Router to keep it consistent with how tools and resources are handled.

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)
Documentation update

Checklist

I have read the MCP Documentation
My code follows the repository's style guidelines
New and existing tests pass locally
I have added appropriate error handling
I have added or updated documentation as needed

Additional context

- add new endpoints `list_prompts` and `get_prompt` in the MCP client - update prompt model in mcp-core to make `description` and `arguments` optional, following MCP spec

salman1993 · 2025-02-21T16:02:52Z

nit: you can add a prompt in the mcp-server example here: https://github.com/modelcontextprotocol/rust-sdk/blob/main/crates/mcp-server/src/main.rs. that'll make it easier to test from this mcp-client example: https://github.com/modelcontextprotocol/rust-sdk/blob/main/crates/mcp-client/examples/stdio_integration.rs

implementing types to define them, similar to other methods

test both new methods

kalvinnchau · 2025-02-21T17:20:18Z

Added the examples, and changed the Router methods to be in-line with tools/resources, which is a breaking change since implementing types will need to define those.

❯ cargo run -p mcp-client --example stdio_integration
...
Prompts: ListPromptsResult { prompts: [Prompt { name: "example_prompt", description: Some("This is an example prompt that takes one required agrument, message"), arguments: Some([PromptArgument { name: "message", description: Some("A message to put in the prompt"), required: Some(true) }]) }] }

...

Prompt: GetPromptResult { description: Some("This is an example prompt with your message here: 'hello there!'"), messages: [PromptMessage { role: User, content: Text { text: "This is an example prompt with your message here: 'hello there!'" } }] }

salman1993 · 2025-02-22T16:14:12Z

lgtm! i don't have write access in this repo

…-spec

…urns Result - Add strip_output() that strips title/description without validating type (Dale modelcontextprotocol#1) - Change schema_for_output to return Arc<JsonObject> instead of Result (Dale modelcontextprotocol#2) - Cache only Arc<JsonObject> success values, not Result (Dale modelcontextprotocol#3) - Remove dead unwrap_or_else panic paths in with_output_schema, ToolBase, and macros - Tighten test assertions from contains to assert_eq on type field (Dale modelcontextprotocol#4) - Update test_schema_for_output_rejects_primitive to accept_primitive (SEP-2106) Co-authored-by: Orca <help@stably.ai>

…2106) (#895) * fix: address PR review - schema_for_output no longer validates or returns Result - Add strip_output() that strips title/description without validating type (Dale #1) - Change schema_for_output to return Arc<JsonObject> instead of Result (Dale #2) - Cache only Arc<JsonObject> success values, not Result (Dale #3) - Remove dead unwrap_or_else panic paths in with_output_schema, ToolBase, and macros - Tighten test assertions from contains to assert_eq on type field (Dale #4) - Update test_schema_for_output_rejects_primitive to accept_primitive (SEP-2106) Co-authored-by: Orca <help@stably.ai> * test(rmcp): add non-object output schema tests for SEP-2106 Add tests verifying schema_for_output accepts non-object types: - test_tool_builder_methods: primitive (i32), array (Vec<String>), option - test_structured_output: tool returning Json<Vec<T>> and Json<i32> - test_json_schema_detection: Json<Vec<T>>, Result<Json<Vec<T>>,E>, Json<String> - tool_traits: ToolBase::output_schema with Vec<AddOutput> output type * test(rmcp): add missing edge case tests from code review Add tests identified during code review: - description stripping for primitive types - composition types (Option<String> with anyOf/oneOf/null) - cache correctness (Arc::ptr_eq for repeated calls) - schema_for_input rejecting array types (not just primitives) - schema_for_output accepting unit type () * feat!: mark schema_for_output return-type change as breaking This introduces SEP-2106: schema_for_output no longer validates or returns Result. The public signature changed, so bump major. * fix: address Dale's PR review - direct schema.get assertions, remove ArrayTool - Replace loose schema_str.contains(...) assertions with direct schema.get("type") equality checks in test_tool_builder_methods.rs and test_structured_output.rs - Remove redundant ArrayTool fixture and its round-trip serde_json::from_str test from tool_traits.rs since schema is already Arc<JsonObject> - Drop dead schema_str variable in test_structured_output.rs --------- Co-authored-by: Brandon Bennett <brandonbennett@macbookair.myfiosgateway.com> Co-authored-by: Orca <help@stably.ai> Co-authored-by: Brandon Bennett <brandonbennett@Pursuits-Air.lan>

kalvinnchau added 2 commits February 20, 2025 19:38

feat: add prompts support to mcp-client, ahere to MCP spec for prompts

08b73f3

- add new endpoints `list_prompts` and `get_prompt` in the MCP client - update prompt model in mcp-core to make `description` and `arguments` optional, following MCP spec

feat: handle JsonRpcMessage::Error messages to propagate to the user

22b11ea

salman1993 approved these changes Feb 21, 2025

View reviewed changes

kalvinnchau added 2 commits February 21, 2025 09:14

feat: remove concrete impl of get_prompt and list_prompts, and require

7afab42

implementing types to define them, similar to other methods

test: add impl of list/get prompt to main.rs and stdio_integration to

ef9309c

test both new methods

alexhancock self-requested a review February 22, 2025 16:40

alexhancock approved these changes Feb 22, 2025

View reviewed changes

alexhancock merged commit 8f3cb34 into modelcontextprotocol:main Feb 22, 2025

takumi-earth pushed a commit to earthlings-dev/rmcp that referenced this pull request Jan 27, 2026

Merge pull request modelcontextprotocol#2 from kalvinnchau/mcp-prompt…

ea85834

…-spec

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feat: update mcp-core prompt to match spec, add mcp list/get to mcp-client#2

feat: update mcp-core prompt to match spec, add mcp list/get to mcp-client#2
alexhancock merged 4 commits into
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kalvinnchau commented Feb 21, 2025 •

edited

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salman1993 commented Feb 21, 2025

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kalvinnchau commented Feb 21, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Motivation and Context

How Has This Been Tested?

Breaking Changes

Types of changes

Checklist

Additional context

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salman1993 commented Feb 21, 2025

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kalvinnchau commented Feb 21, 2025

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salman1993 commented Feb 22, 2025

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kalvinnchau commented Feb 21, 2025 •

edited

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