fix: ensure jsonrpc field is serialized as "2.0"

codex-rs/mcp-types/generate_mcp_types.py

@@ -13,6 +13,8 @@ from pathlib import Path
 # Helper first so it is defined when other functions call it.
 from typing import Any, Literal
 
+SCHEMA_VERSION = "2025-03-26"
+JSONRPC_VERSION = "2.0"
 
 STANDARD_DERIVE = "#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]\n"
 
@@ -30,7 +32,7 @@ def main() -> int:
     num_args = len(sys.argv)
     if num_args == 1:
         schema_file = (
-            Path(__file__).resolve().parent / "schema" / "2025-03-26" / "schema.json"
+            Path(__file__).resolve().parent / "schema" / SCHEMA_VERSION / "schema.json"
         )
     elif num_args == 2:
         schema_file = Path(sys.argv[1])
@@ -48,7 +50,7 @@ def main() -> int:
     DEFINITIONS = schema_json["definitions"]
 
     out = [
-        """
+        f"""
 // @generated
 // DO NOT EDIT THIS FILE DIRECTLY.
 // Run the following in the crate root to regenerate this file:
@@ -61,18 +63,23 @@ use serde::Serialize;
 use serde::de::DeserializeOwned;
 use std::convert::TryFrom;
 
+pub const MCP_SCHEMA_VERSION: &str = "{SCHEMA_VERSION}";
+pub const JSONRPC_VERSION: &str = "{JSONRPC_VERSION}";
+
 /// Paired request/response types for the Model Context Protocol (MCP).
-pub trait ModelContextProtocolRequest {
+pub trait ModelContextProtocolRequest {{
     const METHOD: &'static str;
     type Params: DeserializeOwned + Serialize + Send + Sync + 'static;
     type Result: DeserializeOwned + Serialize + Send + Sync + 'static;
-}
+}}
 
 /// One-way message in the Model Context Protocol (MCP).
-pub trait ModelContextProtocolNotification {
+pub trait ModelContextProtocolNotification {{
     const METHOD: &'static str;
     type Params: DeserializeOwned + Serialize + Send + Sync + 'static;
-}
+}}
+
+fn default_jsonrpc() -> String {{ JSONRPC_VERSION.to_owned() }}
 
 """
     ]
@@ -174,6 +181,10 @@ pub trait ModelContextProtocolNotification {
 
 
 def add_definition(name: str, definition: dict[str, Any], out: list[str]) -> None:
+    if name == "Result":
+        out.append("pub type Result = serde_json::Value;\n\n")
+        return
+
     # Capture description
     description = definition.get("description")
 
@@ -181,6 +192,14 @@ def add_definition(name: str, definition: dict[str, Any], out: list[str]) -> Non
     if properties:
         required_props = set(definition.get("required", []))
         out.extend(define_struct(name, properties, required_props, description))
+
+        # Special carve-out for Result types:
+        if name.endswith("Result"):
+            out.extend(f"impl From<{name}> for serde_json::Value {{\n")
+            out.append(f"    fn from(value: {name}) -> Self {{\n")
+            out.append("        serde_json::to_value(value).unwrap()\n")
+            out.append("    }\n")
+            out.append("}\n\n")
         return
 
     enum_values = definition.get("enum", [])
@@ -245,10 +264,6 @@ class StructField:
     serde: str | None = None
 
     def append(self, out: list[str], supports_const: bool) -> None:
-        # Omit these for now.
-        if self.name == "jsonrpc":
-            return
-
         if self.serde:
             out.append(f"    {self.serde}\n")
         if self.viz == "const":
@@ -273,6 +288,16 @@ def define_struct(
         if prop_name == "_meta":
             # TODO?
             continue
+        elif prop_name == "jsonrpc":
+            fields.append(
+                StructField(
+                    "pub",
+                    "jsonrpc",
+                    "String",  # cannot use `&'static str` because of Deserialize
+                    '#[serde(rename = "jsonrpc", default = "default_jsonrpc")]',
+                )
+            )
+            continue
 
         prop_type = map_type(prop, prop_name, name)
         if prop_name not in required_props:

codex-rs/mcp-types/src/lib.rs

@@ -10,6 +10,9 @@ use serde::Deserialize;
 use serde::Serialize;
 use std::convert::TryFrom;
 
+pub const MCP_SCHEMA_VERSION: &str = "2025-03-26";
+pub const JSONRPC_VERSION: &str = "2.0";
+
 /// Paired request/response types for the Model Context Protocol (MCP).
 pub trait ModelContextProtocolRequest {
     const METHOD: &'static str;
@@ -23,6 +26,10 @@ pub trait ModelContextProtocolNotification {
     type Params: DeserializeOwned + Serialize + Send + Sync + 'static;
 }
 
+fn default_jsonrpc() -> String {
+    JSONRPC_VERSION.to_owned()
+}
+
 /// Optional annotations for the client. The client can use annotations to inform how objects are used or displayed
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct Annotations {
@@ -88,6 +95,12 @@ pub enum CallToolResultContent {
     EmbeddedResource(EmbeddedResource),
 }
 
+impl From<CallToolResult> for serde_json::Value {
+    fn from(value: CallToolResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum CancelledNotification {}
 
@@ -208,6 +221,12 @@ pub struct CompleteResultCompletion {
     pub values: Vec<String>,
 }
 
+impl From<CompleteResult> for serde_json::Value {
+    fn from(value: CompleteResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum CreateMessageRequest {}
 
@@ -251,6 +270,12 @@ pub enum CreateMessageResultContent {
     AudioContent(AudioContent),
 }
 
+impl From<CreateMessageResult> for serde_json::Value {
+    fn from(value: CreateMessageResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct Cursor(String);
 
@@ -295,6 +320,12 @@ pub struct GetPromptResult {
     pub messages: Vec<PromptMessage>,
 }
 
+impl From<GetPromptResult> for serde_json::Value {
+    fn from(value: GetPromptResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 /// An image provided to or from an LLM.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct ImageContent {
@@ -341,6 +372,12 @@ pub struct InitializeResult {
     pub server_info: Implementation,
 }
 
+impl From<InitializeResult> for serde_json::Value {
+    fn from(value: InitializeResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum InitializedNotification {}
 
@@ -370,6 +407,8 @@ pub type JSONRPCBatchResponse = Vec<JSONRPCBatchResponseItem>;
 pub struct JSONRPCError {
     pub error: JSONRPCErrorError,
     pub id: RequestId,
+    #[serde(rename = "jsonrpc", default = "default_jsonrpc")]
+    pub jsonrpc: String,
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
@@ -394,6 +433,8 @@ pub enum JSONRPCMessage {
 /// A notification which does not expect a response.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct JSONRPCNotification {
+    #[serde(rename = "jsonrpc", default = "default_jsonrpc")]
+    pub jsonrpc: String,
     pub method: String,
     pub params: Option<serde_json::Value>,
 }
@@ -402,6 +443,8 @@ pub struct JSONRPCNotification {
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct JSONRPCRequest {
     pub id: RequestId,
+    #[serde(rename = "jsonrpc", default = "default_jsonrpc")]
+    pub jsonrpc: String,
     pub method: String,
     pub params: Option<serde_json::Value>,
 }
@@ -410,6 +453,8 @@ pub struct JSONRPCRequest {
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct JSONRPCResponse {
     pub id: RequestId,
+    #[serde(rename = "jsonrpc", default = "default_jsonrpc")]
+    pub jsonrpc: String,
     pub result: Result,
 }
 
@@ -435,6 +480,12 @@ pub struct ListPromptsResult {
     pub prompts: Vec<Prompt>,
 }
 
+impl From<ListPromptsResult> for serde_json::Value {
+    fn from(value: ListPromptsResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ListResourceTemplatesRequest {}
 
@@ -458,6 +509,12 @@ pub struct ListResourceTemplatesResult {
     pub resource_templates: Vec<ResourceTemplate>,
 }
 
+impl From<ListResourceTemplatesResult> for serde_json::Value {
+    fn from(value: ListResourceTemplatesResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ListResourcesRequest {}
 
@@ -480,6 +537,12 @@ pub struct ListResourcesResult {
     pub resources: Vec<Resource>,
 }
 
+impl From<ListResourcesResult> for serde_json::Value {
+    fn from(value: ListResourcesResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ListRootsRequest {}
 
@@ -497,6 +560,12 @@ pub struct ListRootsResult {
     pub roots: Vec<Root>,
 }
 
+impl From<ListRootsResult> for serde_json::Value {
+    fn from(value: ListRootsResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ListToolsRequest {}
 
@@ -519,6 +588,12 @@ pub struct ListToolsResult {
     pub tools: Vec<Tool>,
 }
 
+impl From<ListToolsResult> for serde_json::Value {
+    fn from(value: ListToolsResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 /// The severity of a log message.
 ///
 /// These map to syslog message severities, as specified in RFC-5424:
@@ -612,6 +687,12 @@ pub struct PaginatedResult {
     pub next_cursor: Option<String>,
 }
 
+impl From<PaginatedResult> for serde_json::Value {
+    fn from(value: PaginatedResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum PingRequest {}
 
@@ -720,6 +801,12 @@ pub enum ReadResourceResultContents {
     BlobResourceContents(BlobResourceContents),
 }
 
+impl From<ReadResourceResult> for serde_json::Value {
+    fn from(value: ReadResourceResult) -> Self {
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct Request {
     pub method: String,
@@ -793,8 +880,7 @@ pub struct ResourceUpdatedNotificationParams {
     pub uri: String,
 }
 
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-pub struct Result {}
+pub type Result = serde_json::Value;
 
 /// The sender or recipient of messages and data in a conversation.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]

codex-rs/mcp-types/tests/initialize.rs

@@ -5,6 +5,7 @@ use mcp_types::InitializeRequestParams;
 use mcp_types::JSONRPCMessage;
 use mcp_types::JSONRPCRequest;
 use mcp_types::RequestId;
+use mcp_types::JSONRPC_VERSION;
 use serde_json::json;
 
 #[test]
@@ -30,6 +31,7 @@ fn deserialize_initialize_request() {
     };
 
     let expected_req = JSONRPCRequest {
+        jsonrpc: JSONRPC_VERSION.into(),
         id: RequestId::Integer(1),
         method: "initialize".into(),
         params: Some(json!({