Prep v0.5.1

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## 0.5.1 (2025-10-24)
+
+- Add ability for agents and clients to provide information about their implementation
+- Fix incorrectly serialized `_meta` field on `SetSessionModeResponse
+
 ## 0.5.0 (2025-10-24)
 
 - Provide access to an `AbortSignal` and `closed` promise on connections so you can wait for the connection to close and handle any other cleanup tasks you need for a graceful shutdown. https://github.com/agentclientprotocol/typescript-sdk/pull/11

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@agentclientprotocol/sdk",
-  "version": "0.5.0",
+  "version": "0.5.1",
   "publishConfig": {
     "access": "public"
   },

schema/schema.json

@@ -958,6 +958,25 @@
       "required": ["name", "value"],
       "type": "object"
     },
+    "Implementation": {
+      "description": "Describes the name and version of an MCP implementation, with an optional\ntitle for UI representation.",
+      "properties": {
+        "name": {
+          "description": "Intended for programmatic or logical use, but can be used as a display\nname fallback if title isn’t present.",
+          "type": "string"
+        },
+        "title": {
+          "description": "Intended for UI and end-user contexts — optimized to be human-readable\nand easily understood.\n\nIf not provided, the name should be used for display.",
+          "type": ["string", "null"]
+        },
+        "version": {
+          "description": "Version of the implementation. Can be displayed to the user or used\nfor debugging or metrics purposes.",
+          "type": "string"
+        }
+      },
+      "required": ["name", "version"],
+      "type": "object"
+    },
     "InitializeRequest": {
       "description": "Request parameters for the initialize method.\n\nSent by the client to establish connection and negotiate capabilities.\n\nSee protocol docs: [Initialization](https://agentclientprotocol.com/protocol/initialization)",
       "properties": {
@@ -975,6 +994,17 @@
           },
           "description": "Capabilities supported by the client."
         },
+        "clientInfo": {
+          "anyOf": [
+            {
+              "$ref": "#/$defs/Implementation"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "description": "Information about the Client name and version sent to the Agent.\n\nNote: in future versions of the protocol, this will be required."
+        },
         "protocolVersion": {
           "$ref": "#/$defs/ProtocolVersion",
           "description": "The latest protocol version supported by the client."
@@ -1007,6 +1037,17 @@
           },
           "description": "Capabilities supported by the agent."
         },
+        "agentInfo": {
+          "anyOf": [
+            {
+              "$ref": "#/$defs/Implementation"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "description": "Information about the Agent name and version sent to the Client.\n\nNote: in future versions of the protocol, this will be required."
+        },
         "authMethods": {
           "default": [],
           "description": "Authentication methods supported by the agent.",
@@ -2050,7 +2091,7 @@
     "SetSessionModeResponse": {
       "description": "Response to `session/set_mode` method.",
       "properties": {
-        "meta": true
+        "_meta": true
       },
       "type": "object",
       "x-method": "session/set_mode",

scripts/generate.js

@@ -5,7 +5,7 @@ import { generate } from "ts-to-zod";
 import * as fs from "fs/promises";
 import { dirname } from "path";
 
-const CURRENT_SCHEMA_RELEASE = "v0.5.0";
+const CURRENT_SCHEMA_RELEASE = "v0.6.2";
 
 await downloadSchemas(CURRENT_SCHEMA_RELEASE);
 

src/schema.ts

@@ -870,6 +870,12 @@ export interface InitializeResponse {
     [k: string]: unknown;
   };
   agentCapabilities?: AgentCapabilities;
+  /**
+   * Information about the Agent name and version sent to the Client.
+   *
+   * Note: in future versions of the protocol, this will be required.
+   */
+  agentInfo?: Implementation | null;
   /**
    * Authentication methods supported by the agent.
    */
@@ -944,6 +950,29 @@ export interface PromptCapabilities {
    */
   image?: boolean;
 }
+/**
+ * Describes the name and version of an MCP implementation, with an optional
+ * title for UI representation.
+ */
+export interface Implementation {
+  /**
+   * Intended for programmatic or logical use, but can be used as a display
+   * name fallback if title isn’t present.
+   */
+  name: string;
+  /**
+   * Intended for UI and end-user contexts — optimized to be human-readable
+   * and easily understood.
+   *
+   * If not provided, the name should be used for display.
+   */
+  title?: string | null;
+  /**
+   * Version of the implementation. Can be displayed to the user or used
+   * for debugging or metrics purposes.
+   */
+  version: string;
+}
 /**
  * Describes an available authentication method.
  */
@@ -1125,7 +1154,7 @@ export interface LoadSessionResponse {
  * Response to `session/set_mode` method.
  */
 export interface SetSessionModeResponse {
-  meta?: unknown;
+  _meta?: unknown;
 }
 /**
  * Response from processing a user prompt.
@@ -1707,6 +1736,12 @@ export interface InitializeRequest {
     [k: string]: unknown;
   };
   clientCapabilities?: ClientCapabilities;
+  /**
+   * Information about the Client name and version sent to the Agent.
+   *
+   * Note: in future versions of the protocol, this will be required.
+   */
+  clientInfo?: Implementation | null;
   /**
    * The latest protocol version supported by the client.
    */
@@ -2284,7 +2319,7 @@ export const authenticateResponseSchema = z.object({
 
 /** @internal */
 export const setSessionModeResponseSchema = z.object({
-  meta: z.unknown().optional(),
+  _meta: z.unknown().optional(),
 });
 
 /** @internal */
@@ -2516,6 +2551,13 @@ export const envVariableSchema = z.object({
   value: z.string(),
 });
 
+/** @internal */
+export const implementationSchema = z.object({
+  name: z.string(),
+  title: z.string().optional().nullable(),
+  version: z.string(),
+});
+
 /** @internal */
 export const authMethodSchema = z.object({
   _meta: z.record(z.unknown()).optional(),
@@ -2798,6 +2840,7 @@ export const requestSchema = z.object({
 export const initializeResponseSchema = z.object({
   _meta: z.record(z.unknown()).optional(),
   agentCapabilities: agentCapabilitiesSchema.optional(),
+  agentInfo: implementationSchema.optional().nullable(),
   authMethods: z.array(authMethodSchema).optional(),
   protocolVersion: z.number(),
 });
@@ -3005,6 +3048,7 @@ export const sessionNotificationSchema = z.object({
 export const initializeRequestSchema = z.object({
   _meta: z.record(z.unknown()).optional(),
   clientCapabilities: clientCapabilitiesSchema.optional(),
+  clientInfo: implementationSchema.optional().nullable(),
   protocolVersion: z.number(),
 });