feat!: remove Zod schemas from public API

README.md

@@ -39,7 +39,7 @@ This monorepo publishes split packages:
 - **`@modelcontextprotocol/server`**: build MCP servers
 - **`@modelcontextprotocol/client`**: build MCP clients
 
-Both packages have a **required peer dependency** on `zod` for schema validation. The SDK internally imports from `zod/v4`, but remains compatible with projects using Zod v3.25+.
+Both packages have a **required peer dependency** on `zod` for schema validation. The SDK uses Zod v4.
 
 ### Middleware packages (optional)
 

examples/client/src/elicitationUrlExample.ts

@@ -656,7 +656,7 @@ async function listTools(): Promise<void> {
             method: 'tools/list',
             params: {}
         };
-        const toolsResult = await client.request(toolsRequest, ListToolsResultSchema);
+        const toolsResult = await client.request(toolsRequest);
 
         console.log('Available tools:');
         if (toolsResult.tools.length === 0) {
@@ -687,7 +687,7 @@ async function callTool(name: string, args: Record<string, unknown>): Promise<vo
         };
 
         console.log(`Calling tool '${name}' with args:`, args);
-        const result = await client.request(request, CallToolResultSchema);
+        const result = await client.request(request);
 
         console.log('Tool result:');
         const resourceLinks: ResourceLink[] = [];

examples/client/src/multipleClientsParallel.ts

@@ -60,7 +60,7 @@ async function createAndRunClient(config: ClientConfig): Promise<{ id: string; r
             }
         };
 
-        const result = await client.request(toolRequest, CallToolResultSchema);
+        const result = await client.request(toolRequest);
         console.log(`[${config.id}] Tool call completed`);
 
         // Keep the connection open for a bit to receive notifications

examples/client/src/parallelToolCallsClient.ts

@@ -1,5 +1,5 @@
-import type { CallToolResult, ListToolsRequest } from '@modelcontextprotocol/client';
-import { CallToolResultSchema, Client, ListToolsResultSchema, StreamableHTTPClientTransport } from '@modelcontextprotocol/client';
+import type { CallToolRequest, CallToolResult, ListToolsRequest } from '@modelcontextprotocol/client';
+import { Client, StreamableHTTPClientTransport } from '@modelcontextprotocol/client';
 
 /**
  * Parallel Tool Calls MCP Client
@@ -86,7 +86,7 @@ async function listTools(client: Client): Promise<void> {
             method: 'tools/list',
             params: {}
         };
-        const toolsResult = await client.request(toolsRequest, ListToolsResultSchema);
+        const toolsResult = await client.request(toolsRequest);
 
         console.log('Available tools:');
         if (toolsResult.tools.length === 0) {
@@ -159,7 +159,7 @@ async function startParallelNotificationTools(client: Client): Promise<Record<st
         const toolPromises = toolCalls.map(({ caller, request }) => {
             console.log(`Starting tool call for ${caller}...`);
             return client
-                .request(request, CallToolResultSchema)
+                .request(request as CallToolRequest)
                 .then(result => ({ caller, result }))
                 .catch(error => {
                     console.error(`Error in tool call for ${caller}:`, error);

examples/client/src/simpleOAuthClient.ts

@@ -252,7 +252,7 @@ class InteractiveOAuthClient {
                 params: {}
             };
 
-            const result = await this.client.request(request, ListToolsResultSchema);
+            const result = await this.client.request(request);
 
             if (result.tools && result.tools.length > 0) {
                 console.log('\n📋 Available tools:');
@@ -310,7 +310,7 @@ class InteractiveOAuthClient {
                 }
             };
 
-            const result = await this.client.request(request, CallToolResultSchema);
+            const result = await this.client.request(request);
 
             console.log(`\n🔧 Tool '${toolName}' result:`);
             if (result.content) {

examples/client/src/simpleStreamableHttp.ts

@@ -2,6 +2,7 @@ import { createInterface } from 'node:readline';
 
 import type {
     CallToolRequest,
+    ElicitResult,
     GetPromptRequest,
     ListPromptsRequest,
     ListResourcesRequest,
@@ -268,7 +269,7 @@ async function connect(url?: string): Promise<void> {
         };
 
         // Set up elicitation request handler with proper validation
-        client.setRequestHandler('elicitation/create', async request => {
+        client.setRequestHandler('elicitation/create', async (request): Promise<ElicitResult> => {
             if (request.params.mode !== 'form') {
                 throw new McpError(ErrorCode.InvalidParams, `Unsupported elicitation mode: ${request.params.mode}`);
             }
@@ -293,7 +294,7 @@ async function connect(url?: string): Promise<void> {
                 attempts++;
                 console.log(`\nPlease provide the following information (attempt ${attempts}/${maxAttempts}):`);
 
-                const content: Record<string, unknown> = {};
+                const content: Record<string, string | number | boolean | string[]> = {};
                 let inputCancelled = false;
 
                 // Collect input for each field
@@ -357,15 +358,15 @@ async function connect(url?: string): Promise<void> {
                     // Parse and validate the input
                     try {
                         if (answer === '' && field.default !== undefined) {
-                            content[fieldName] = field.default;
+                            content[fieldName] = field.default as string | number | boolean | string[];
                         } else if (answer === '' && !isRequired) {
                             // Skip optional empty fields
                             continue;
                         } else if (answer === '') {
                             throw new Error(`${fieldName} is required`);
                         } else {
                             // Parse the value based on type
-                            let parsedValue: unknown;
+                            let parsedValue: string | number | boolean | string[];
 
                             switch (field.type) {
                                 case 'boolean': {
@@ -375,15 +376,15 @@ async function connect(url?: string): Promise<void> {
                                 }
                                 case 'number': {
                                     parsedValue = Number.parseFloat(answer);
-                                    if (Number.isNaN(parsedValue as number)) {
+                                    if (Number.isNaN(parsedValue)) {
                                         throw new TypeError(`${fieldName} must be a valid number`);
                                     }
 
                                     break;
                                 }
                                 case 'integer': {
                                     parsedValue = Number.parseInt(answer, 10);
-                                    if (Number.isNaN(parsedValue as number)) {
+                                    if (Number.isNaN(parsedValue)) {
                                         throw new TypeError(`${fieldName} must be a valid integer`);
                                     }
 
@@ -511,8 +512,7 @@ async function connect(url?: string): Promise<void> {
                     {
                         method: 'resources/list',
                         params: {}
-                    },
-                    ListResourcesResultSchema
+                    }
                 );
                 console.log('Available resources count:', resourcesResult.resources.length);
             } catch {
@@ -598,7 +598,7 @@ async function listTools(): Promise<void> {
             method: 'tools/list',
             params: {}
         };
-        const toolsResult = await client.request(toolsRequest, ListToolsResultSchema);
+        const toolsResult = await client.request(toolsRequest);
 
         console.log('Available tools:');
         if (toolsResult.tools.length === 0) {
@@ -629,7 +629,7 @@ async function callTool(name: string, args: Record<string, unknown>): Promise<vo
         };
 
         console.log(`Calling tool '${name}' with args:`, args);
-        const result = await client.request(request, CallToolResultSchema);
+        const result = await client.request(request);
 
         console.log('Tool result:');
         const resourceLinks: ResourceLink[] = [];
@@ -727,7 +727,7 @@ async function runNotificationsToolWithResumability(interval: number, count: num
             console.log(`Updated resumption token: ${event}`);
         };
 
-        const result = await client.request(request, CallToolResultSchema, {
+        const result = await client.request(request, {
             resumptionToken: notificationsToolLastEventId,
             onresumptiontoken: onLastEventIdUpdate
         });
@@ -756,7 +756,7 @@ async function listPrompts(): Promise<void> {
             method: 'prompts/list',
             params: {}
         };
-        const promptsResult = await client.request(promptsRequest, ListPromptsResultSchema);
+        const promptsResult = await client.request(promptsRequest);
         console.log('Available prompts:');
         if (promptsResult.prompts.length === 0) {
             console.log('  No prompts available');
@@ -785,7 +785,7 @@ async function getPrompt(name: string, args: Record<string, unknown>): Promise<v
             }
         };
 
-        const promptResult = await client.request(promptRequest, GetPromptResultSchema);
+        const promptResult = await client.request(promptRequest);
         console.log('Prompt template:');
         for (const [index, msg] of promptResult.messages.entries()) {
             console.log(`  [${index + 1}] ${msg.role}: ${msg.content.type === 'text' ? msg.content.text : JSON.stringify(msg.content)}`);
@@ -806,7 +806,7 @@ async function listResources(): Promise<void> {
             method: 'resources/list',
             params: {}
         };
-        const resourcesResult = await client.request(resourcesRequest, ListResourcesResultSchema);
+        const resourcesResult = await client.request(resourcesRequest);
 
         console.log('Available resources:');
         if (resourcesResult.resources.length === 0) {
@@ -834,7 +834,7 @@ async function readResource(uri: string): Promise<void> {
         };
 
         console.log(`Reading resource: ${uri}`);
-        const result = await client.request(request, ReadResourceResultSchema);
+        const result = await client.request(request);
 
         console.log('Resource contents:');
         for (const content of result.contents) {

examples/client/src/ssePollingClient.ts

@@ -78,10 +78,9 @@ async function main(): Promise<void> {
                     arguments: {}
                 }
             },
-            CallToolResultSchema,
             {
                 // Track resumption tokens for debugging
-                onresumptiontoken: token => {
+                onresumptiontoken: (token: string) => {
                     lastEventId = token;
                     console.log(`[Event ID] ${token}`);
                 }

examples/client/src/streamableHttpWithSseFallbackClient.ts

@@ -135,7 +135,7 @@ async function listTools(client: Client): Promise<void> {
             method: 'tools/list',
             params: {}
         };
-        const toolsResult = await client.request(toolsRequest, ListToolsResultSchema);
+        const toolsResult = await client.request(toolsRequest);
 
         console.log('Available tools:');
         if (toolsResult.tools.length === 0) {
@@ -168,7 +168,7 @@ async function startNotificationTool(client: Client): Promise<void> {
         };
 
         console.log('Calling notification tool...');
-        const result = await client.request(request, CallToolResultSchema);
+        const result = await client.request(request);
 
         console.log('Tool result:');
         for (const item of result.content) {

examples/server/src/simpleStreamableHttp.ts

@@ -247,8 +247,7 @@ const getServer = () => {
                             message,
                             requestedSchema
                         }
-                    },
-                    ElicitResultSchema
+                    }
                 );
 
                 if (result.action === 'accept') {