chore: support MCP schema 2025-06-18 (#1621)

This updates the schema in `generate_mcp_types.py` from `2025-03-26` to
`2025-06-18`, regenerates `mcp-types/src/lib.rs`, and then updates all
the code that uses `mcp-types` to honor the changes.

Ran

```
npx @modelcontextprotocol/inspector just codex mcp
```

and verified that I was able to invoke the `codex` tool, as expected.


---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/1621).
* #1623
* #1622
* __->__ #1621

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

@@ -10,7 +10,7 @@ use serde::Serialize;
 use serde::de::DeserializeOwned;
 use std::convert::TryFrom;
 
-pub const MCP_SCHEMA_VERSION: &str = "2025-03-26";
+pub const MCP_SCHEMA_VERSION: &str = "2025-06-18";
 pub const JSONRPC_VERSION: &str = "2.0";
 
 /// Paired request/response types for the Model Context Protocol (MCP).
@@ -35,6 +35,12 @@ fn default_jsonrpc() -> String {
 pub struct Annotations {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub audience: Option<Vec<Role>>,
+    #[serde(
+        rename = "lastModified",
+        default,
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub last_modified: Option<String>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub priority: Option<f64>,
 }
@@ -50,6 +56,14 @@ pub struct AudioContent {
     pub r#type: String, // &'static str = "audio"
 }
 
+/// Base interface for metadata with name (identifier) and title (display name) properties.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct BaseMetadata {
+    pub name: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct BlobResourceContents {
     pub blob: String,
@@ -58,6 +72,17 @@ pub struct BlobResourceContents {
     pub uri: String,
 }
 
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct BooleanSchema {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub default: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    pub r#type: String, // &'static str = "boolean"
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum CallToolRequest {}
 
@@ -75,29 +100,17 @@ pub struct CallToolRequestParams {
 }
 
 /// The server's response to a tool call.
-///
-/// Any errors that originate from the tool SHOULD be reported inside the result
-/// object, with `isError` set to true, _not_ as an MCP protocol-level error
-/// response. Otherwise, the LLM would not be able to see that an error occurred
-/// and self-correct.
-///
-/// However, any errors in _finding_ the tool, an error indicating that the
-/// server does not support tool calls, or any other exceptional conditions,
-/// should be reported as an MCP error response.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct CallToolResult {
-    pub content: Vec<CallToolResultContent>,
+    pub content: Vec<ContentBlock>,
     #[serde(rename = "isError", default, skip_serializing_if = "Option::is_none")]
     pub is_error: Option<bool>,
-}
-
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-#[serde(untagged)]
-pub enum CallToolResultContent {
-    TextContent(TextContent),
-    ImageContent(ImageContent),
-    AudioContent(AudioContent),
-    EmbeddedResource(EmbeddedResource),
+    #[serde(
+        rename = "structuredContent",
+        default,
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub structured_content: Option<serde_json::Value>,
 }
 
 impl From<CallToolResult> for serde_json::Value {
@@ -127,6 +140,8 @@ pub struct CancelledNotificationParams {
 /// Capabilities a client may support. Known capabilities are defined here, in this schema, but this is not a closed set: any client can define its own, additional capabilities.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct ClientCapabilities {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub elicitation: Option<serde_json::Value>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub experimental: Option<serde_json::Value>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -194,6 +209,7 @@ pub enum ClientResult {
     Result(Result),
     CreateMessageResult(CreateMessageResult),
     ListRootsResult(ListRootsResult),
+    ElicitResult(ElicitResult),
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
@@ -208,9 +224,18 @@ impl ModelContextProtocolRequest for CompleteRequest {
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct CompleteRequestParams {
     pub argument: CompleteRequestParamsArgument,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub context: Option<CompleteRequestParamsContext>,
     pub r#ref: CompleteRequestParamsRef,
 }
 
+/// Additional, optional context for completions
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct CompleteRequestParamsContext {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub arguments: Option<serde_json::Value>,
+}
+
 /// The argument's information
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct CompleteRequestParamsArgument {
@@ -222,7 +247,7 @@ pub struct CompleteRequestParamsArgument {
 #[serde(untagged)]
 pub enum CompleteRequestParamsRef {
     PromptReference(PromptReference),
-    ResourceReference(ResourceReference),
+    ResourceTemplateReference(ResourceTemplateReference),
 }
 
 /// The server's response to a completion/complete request
@@ -248,6 +273,16 @@ impl From<CompleteResult> for serde_json::Value {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum ContentBlock {
+    TextContent(TextContent),
+    ImageContent(ImageContent),
+    AudioContent(AudioContent),
+    ResourceLink(ResourceLink),
+    EmbeddedResource(EmbeddedResource),
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum CreateMessageRequest {}
 
@@ -325,6 +360,48 @@ impl From<CreateMessageResult> for serde_json::Value {
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct Cursor(String);
 
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub enum ElicitRequest {}
+
+impl ModelContextProtocolRequest for ElicitRequest {
+    const METHOD: &'static str = "elicitation/create";
+    type Params = ElicitRequestParams;
+    type Result = ElicitResult;
+}
+
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ElicitRequestParams {
+    pub message: String,
+    #[serde(rename = "requestedSchema")]
+    pub requested_schema: ElicitRequestParamsRequestedSchema,
+}
+
+/// A restricted subset of JSON Schema.
+/// Only top-level properties are allowed, without nesting.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ElicitRequestParamsRequestedSchema {
+    pub properties: serde_json::Value,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub required: Option<Vec<String>>,
+    pub r#type: String, // &'static str = "object"
+}
+
+/// The client's response to an elicitation request.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ElicitResult {
+    pub action: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub content: Option<serde_json::Value>,
+}
+
+impl From<ElicitResult> for serde_json::Value {
+    fn from(value: ElicitResult) -> Self {
+        // Leave this as it should never fail
+        #[expect(clippy::unwrap_used)]
+        serde_json::to_value(value).unwrap()
+    }
+}
+
 /// The contents of a resource, embedded into a prompt or tool call result.
 ///
 /// It is up to the client how best to render embedded resources for the benefit
@@ -346,6 +423,18 @@ pub enum EmbeddedResourceResource {
 
 pub type EmptyResult = Result;
 
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct EnumSchema {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    pub r#enum: Vec<String>,
+    #[serde(rename = "enumNames", default, skip_serializing_if = "Option::is_none")]
+    pub enum_names: Option<Vec<String>>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    pub r#type: String, // &'static str = "string"
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum GetPromptRequest {}
 
@@ -389,10 +478,12 @@ pub struct ImageContent {
     pub r#type: String, // &'static str = "image"
 }
 
-/// Describes the name and version of an MCP implementation.
+/// Describes the name and version of an MCP implementation, with an optional title for UI representation.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct Implementation {
     pub name: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
     pub version: String,
 }
 
@@ -442,24 +533,6 @@ impl ModelContextProtocolNotification for InitializedNotification {
     type Params = Option<serde_json::Value>;
 }
 
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-#[serde(untagged)]
-pub enum JSONRPCBatchRequestItem {
-    JSONRPCRequest(JSONRPCRequest),
-    JSONRPCNotification(JSONRPCNotification),
-}
-
-pub type JSONRPCBatchRequest = Vec<JSONRPCBatchRequestItem>;
-
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-#[serde(untagged)]
-pub enum JSONRPCBatchResponseItem {
-    JSONRPCResponse(JSONRPCResponse),
-    JSONRPCError(JSONRPCError),
-}
-
-pub type JSONRPCBatchResponse = Vec<JSONRPCBatchResponseItem>;
-
 /// A response to a request that indicates an error occurred.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct JSONRPCError {
@@ -483,10 +556,8 @@ pub struct JSONRPCErrorError {
 pub enum JSONRPCMessage {
     Request(JSONRPCRequest),
     Notification(JSONRPCNotification),
-    BatchRequest(JSONRPCBatchRequest),
     Response(JSONRPCResponse),
     Error(JSONRPCError),
-    BatchResponse(JSONRPCBatchResponse),
 }
 
 /// A notification which does not expect a response.
@@ -777,6 +848,19 @@ pub struct Notification {
     pub params: Option<serde_json::Value>,
 }
 
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct NumberSchema {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub maximum: Option<i64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub minimum: Option<i64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    pub r#type: String,
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct PaginatedRequest {
     pub method: String,
@@ -817,6 +901,17 @@ impl ModelContextProtocolRequest for PingRequest {
     type Result = Result;
 }
 
+/// Restricted schema definitions that only allow primitive types
+/// without nested objects or arrays.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum PrimitiveSchemaDefinition {
+    StringSchema(StringSchema),
+    NumberSchema(NumberSchema),
+    BooleanSchema(BooleanSchema),
+    EnumSchema(EnumSchema),
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ProgressNotification {}
 
@@ -851,6 +946,8 @@ pub struct Prompt {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub description: Option<String>,
     pub name: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
 }
 
 /// Describes an argument that a prompt can accept.
@@ -861,6 +958,8 @@ pub struct PromptArgument {
     pub name: String,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub required: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
@@ -877,23 +976,16 @@ impl ModelContextProtocolNotification for PromptListChangedNotification {
 /// resources from the MCP server.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct PromptMessage {
-    pub content: PromptMessageContent,
+    pub content: ContentBlock,
     pub role: Role,
 }
 
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-#[serde(untagged)]
-pub enum PromptMessageContent {
-    TextContent(TextContent),
-    ImageContent(ImageContent),
-    AudioContent(AudioContent),
-    EmbeddedResource(EmbeddedResource),
-}
-
 /// Identifies a prompt.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct PromptReference {
     pub name: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
     pub r#type: String, // &'static str = "ref/prompt"
 }
 
@@ -958,6 +1050,8 @@ pub struct Resource {
     pub name: String,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub size: Option<i64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
     pub uri: String,
 }
 
@@ -969,6 +1063,26 @@ pub struct ResourceContents {
     pub uri: String,
 }
 
+/// A resource that the server is capable of reading, included in a prompt or tool call result.
+///
+/// Note: resource links returned by tools are not guaranteed to appear in the results of `resources/list` requests.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ResourceLink {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub annotations: Option<Annotations>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    #[serde(rename = "mimeType", default, skip_serializing_if = "Option::is_none")]
+    pub mime_type: Option<String>,
+    pub name: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub size: Option<i64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    pub r#type: String, // &'static str = "resource_link"
+    pub uri: String,
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ResourceListChangedNotification {}
 
@@ -977,13 +1091,6 @@ impl ModelContextProtocolNotification for ResourceListChangedNotification {
     type Params = Option<serde_json::Value>;
 }
 
-/// A reference to a resource or resource template definition.
-#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-pub struct ResourceReference {
-    pub r#type: String, // &'static str = "ref/resource"
-    pub uri: String,
-}
-
 /// A template description for resources available on the server.
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub struct ResourceTemplate {
@@ -994,10 +1101,19 @@ pub struct ResourceTemplate {
     #[serde(rename = "mimeType", default, skip_serializing_if = "Option::is_none")]
     pub mime_type: Option<String>,
     pub name: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
     #[serde(rename = "uriTemplate")]
     pub uri_template: String,
 }
 
+/// A reference to a resource or resource template definition.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ResourceTemplateReference {
+    pub r#type: String, // &'static str = "ref/resource"
+    pub uri: String,
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum ResourceUpdatedNotification {}
 
@@ -1140,6 +1256,7 @@ pub enum ServerRequest {
     PingRequest(PingRequest),
     CreateMessageRequest(CreateMessageRequest),
     ListRootsRequest(ListRootsRequest),
+    ElicitRequest(ElicitRequest),
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
@@ -1172,6 +1289,21 @@ pub struct SetLevelRequestParams {
     pub level: LoggingLevel,
 }
 
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct StringSchema {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub format: Option<String>,
+    #[serde(rename = "maxLength", default, skip_serializing_if = "Option::is_none")]
+    pub max_length: Option<i64>,
+    #[serde(rename = "minLength", default, skip_serializing_if = "Option::is_none")]
+    pub min_length: Option<i64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    pub r#type: String, // &'static str = "string"
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
 pub enum SubscribeRequest {}
 
@@ -1213,6 +1345,25 @@ pub struct Tool {
     #[serde(rename = "inputSchema")]
     pub input_schema: ToolInputSchema,
     pub name: String,
+    #[serde(
+        rename = "outputSchema",
+        default,
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub output_schema: Option<ToolOutputSchema>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+}
+
+/// An optional JSON Schema object defining the structure of the tool's output returned in
+/// the structuredContent field of a CallToolResult.
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ToolOutputSchema {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub properties: Option<serde_json::Value>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub required: Option<Vec<String>>,
+    pub r#type: String, // &'static str = "object"
 }
 
 /// A JSON Schema object defining the expected parameters for the tool.