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MCP Protocol: Align tool-call response with CallToolResult [Stack 1/3] (#1750)

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# Summary
- Align MCP server responses with mcp_types by emitting [CallToolResult,
RequestId] instead of an object.
Update send-message result to a tagged enum: Ok or Error { message }.

# Why
Protocol compliance with current MCP schema.

# Tests
- Updated assertions in mcp_protocol.rs for create/stream/send/list and
error cases.

This is the first PR in a stack.
Stack:
Final: #1686
Intermediate: #1751
First: #1750
This commit is contained in:
aibrahim-oai
2025-07-31 19:30:03 -07:00
committed by GitHub
parent 575590e4c2
commit d3aa5f46b7
1 changed files with 74 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

92
codex-rs/mcp-server/src/mcp_protocol.rs
View File

@@ -7,7 +7,10 @@ use serde::Serialize;
use strum_macros::Display;
use uuid::Uuid;
use mcp_types::CallToolResult;
use mcp_types::ContentBlock;
use mcp_types::RequestId;
use mcp_types::TextContent;
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(transparent)]
@@ -118,10 +121,47 @@ pub struct ToolCallResponse {
pub request_id: RequestId,
#[serde(default, skip_serializing_if = "Option::is_none")]
pub is_error: Option<bool>,
#[serde(default, skip_serializing_if = "Option::is_none")]
#[serde(default, skip_serializing_if = "Option::is_none", flatten)]
pub result: Option<ToolCallResponseResult>,
}
impl From<ToolCallResponse> for CallToolResult {
fn from(val: ToolCallResponse) -> Self {
let ToolCallResponse {
request_id: _request_id,
is_error,
result,
} = val;
let (content, structured_content, is_error_out) = match result {
Some(res) => match serde_json::to_value(&res) {
Ok(v) => {
let content = vec![ContentBlock::TextContent(TextContent {
r#type: "text".to_string(),
text: v.to_string(),
annotations: None,
})];
(content, Some(v), is_error)
}
Err(e) => {
let content = vec![ContentBlock::TextContent(TextContent {
r#type: "text".to_string(),
text: format!("Failed to serialize tool result: {e}"),
annotations: None,
})];
(content, None, Some(true))
}
},
None => (vec![], None, is_error),
};
CallToolResult {
content,
is_error: is_error_out,
structured_content,
}
}
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(untagged)]
pub enum ToolCallResponseResult {
@@ -141,8 +181,10 @@ pub struct ConversationCreateResult {
pub struct ConversationStreamResult {}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct ConversationSendMessageResult {
pub success: bool,
#[serde(tag = "status", rename_all = "camelCase")]
pub enum ConversationSendMessageResult {
Ok,
Error { message: String },
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
@@ -455,10 +497,13 @@ mod tests {
},
)),
};
let observed = to_val(&env);
let req_id = env.request_id.clone();
let observed = to_val(&CallToolResult::from(env));
let expected = json!({
"requestId": 1,
"result": {
"content": [
{ "type": "text", "text": "{\"conversation_id\":\"d0f6ecbe-84a2-41c1-b23d-b20473b25eab\",\"model\":\"o3\"}" }
],
"structuredContent": {
"conversation_id": "d0f6ecbe-84a2-41c1-b23d-b20473b25eab",
"model": "o3"
}
@@ -467,6 +512,7 @@ mod tests {
observed, expected,
"response (ConversationCreate) must match"
);
assert_eq!(req_id, RequestId::Integer(1));
}
#[test]
@@ -478,15 +524,17 @@ mod tests {
ConversationStreamResult {},
)),
};
let observed = to_val(&env);
let req_id = env.request_id.clone();
let observed = to_val(&CallToolResult::from(env));
let expected = json!({
"requestId": 2,
"result": {}
"content": [ { "type": "text", "text": "{}" } ],
"structuredContent": {}
});
assert_eq!(
observed, expected,
"response (ConversationStream) must have empty object result"
);
assert_eq!(req_id, RequestId::Integer(2));
}
#[test]
@@ -495,18 +543,20 @@ mod tests {
request_id: RequestId::Integer(3),
is_error: None,
result: Some(ToolCallResponseResult::ConversationSendMessage(
ConversationSendMessageResult { success: true },
ConversationSendMessageResult::Ok,
)),
};
let observed = to_val(&env);
let req_id = env.request_id.clone();
let observed = to_val(&CallToolResult::from(env));
let expected = json!({
"requestId": 3,
"result": { "success": true }
"content": [ { "type": "text", "text": "{\"status\":\"ok\"}" } ],
"structuredContent": { "status": "ok" }
});
assert_eq!(
observed, expected,
"response (ConversationSendMessageAccepted) must match"
);
assert_eq!(req_id, RequestId::Integer(3));
}
#[test]
@@ -526,10 +576,13 @@ mod tests {
},
)),
};
let observed = to_val(&env);
let req_id = env.request_id.clone();
let observed = to_val(&CallToolResult::from(env));
let expected = json!({
"requestId": 4,
"result": {
"content": [
{ "type": "text", "text": "{\"conversations\":[{\"conversation_id\":\"67e55044-10b1-426f-9247-bb680e5fe0c8\",\"title\":\"Refactor config loader\"}],\"next_cursor\":\"next123\"}" }
],
"structuredContent": {
"conversations": [
{
"conversation_id": "67e55044-10b1-426f-9247-bb680e5fe0c8",
@@ -543,6 +596,7 @@ mod tests {
observed, expected,
"response (ConversationsList with cursor) must match"
);
assert_eq!(req_id, RequestId::Integer(4));
}
#[test]
@@ -552,15 +606,17 @@ mod tests {
is_error: Some(true),
result: None,
};
let observed = to_val(&env);
let req_id = env.request_id.clone();
let observed = to_val(&CallToolResult::from(env));
let expected = json!({
"requestId": 4,
"content": [],
"isError": true
});
assert_eq!(
observed, expected,
"error response must omit `result` and include `isError`"
);
assert_eq!(req_id, RequestId::Integer(4));
}
// ----- Notifications -----