Make the draft-spec scenarios internally consistent (fixes #311, #312, #315)

examples/clients/typescript/everything-client.ts

@@ -155,7 +155,12 @@ async function runRequestMetadataClient(serverUrl: string): Promise<void> {
       const clone = response.clone();
       try {
         const errorResult = await clone.json();
-        if (errorResult.error?.code === -32001) {
+        // -32004 is UnsupportedProtocolVersionError in the draft schema;
+        // -32001 is tolerated for servers that predate the dedicated code.
+        if (
+          errorResult.error?.code === -32004 ||
+          errorResult.error?.code === -32001
+        ) {
           logger.debug(
             'Received UnsupportedProtocolVersionError, starting negotiation...'
           );

examples/servers/typescript/everything-server.ts

@@ -1227,13 +1227,13 @@ app.post('/mcp', async (req, res) => {
       });
     }
 
-    // Protocol Version Negotiation Matrix (-32602, HTTP 400)
+    // Protocol Version Negotiation Matrix (-32004, HTTP 400)
     if (metaVersion !== 'DRAFT-2026-v1') {
       return res.status(400).json({
         jsonrpc: '2.0',
         id,
         error: {
-          code: -32602,
+          code: -32004,
           message: 'UnsupportedProtocolVersionError',
           data: { supported: ['DRAFT-2026-v1'] }
         }
@@ -1296,7 +1296,10 @@ app.post('/mcp', async (req, res) => {
           supportedVersions: ['DRAFT-2026-v1'],
           capabilities: {
             tools: { listChanged: true }, // Explicitly announce dynamic capabilities matching Section 7 expectations
-            prompts: { listChanged: true }
+            prompts: { listChanged: true },
+            // resources/list, resources/templates/list and resources/read are
+            // served on this path, so the capability must be declared too.
+            resources: {}
           },
           serverInfo: { name: 'everything-stateless-server', version: '1.0.0' }
         }
@@ -1371,7 +1374,10 @@ app.post('/mcp', async (req, res) => {
               description: 'Diagnostic logging validator tool',
               inputSchema: { type: 'object', properties: {} }
             }
-          ]
+          ],
+          // SEP-2549 caching hints are required on cacheable list results.
+          ttlMs: 300000,
+          cacheScope: 'public'
         }
       });
     }
@@ -1387,7 +1393,9 @@ app.post('/mcp', async (req, res) => {
               name: 'test_input_required_result_prompt',
               description: 'MRTR: prompt that requires elicitation input'
             }
-          ]
+          ],
+          ttlMs: 300000,
+          cacheScope: 'public'
         }
       });
     }
@@ -1442,6 +1450,69 @@ app.post('/mcp', async (req, res) => {
       }
     }
 
+    // Resources on the stateless path (SEP-2575): SEP-2549 hints + SEP-2164 errors.
+    if (method === 'resources/list') {
+      return res.json({
+        jsonrpc: '2.0',
+        id,
+        result: {
+          resources: [
+            {
+              uri: 'test://stateless-static-text',
+              name: 'Stateless Static Text',
+              description: 'A static text resource served on the draft path',
+              mimeType: 'text/plain'
+            }
+          ],
+          ttlMs: 300000,
+          cacheScope: 'public'
+        }
+      });
+    }
+
+    if (method === 'resources/templates/list') {
+      return res.json({
+        jsonrpc: '2.0',
+        id,
+        result: {
+          resourceTemplates: [],
+          ttlMs: 300000,
+          cacheScope: 'public'
+        }
+      });
+    }
+
+    if (method === 'resources/read') {
+      const uri = params.uri as string | undefined;
+      if (uri === 'test://stateless-static-text') {
+        return res.json({
+          jsonrpc: '2.0',
+          id,
+          result: {
+            contents: [
+              {
+                uri,
+                mimeType: 'text/plain',
+                text: 'Static text content from the stateless draft path.'
+              }
+            ],
+            ttlMs: 300000,
+            cacheScope: 'private'
+          }
+        });
+      }
+      // SEP-2164: unknown resources get -32602 with the requested uri in data.
+      return res.status(200).json({
+        jsonrpc: '2.0',
+        id,
+        error: {
+          code: -32602,
+          message: 'Resource not found',
+          data: { uri }
+        }
+      });
+    }
+
     if (method === 'tools/call') {
       const name = params.name;
       const inputResponses = params.inputResponses as

examples/servers/typescript/sep-2164-empty-contents.ts

@@ -3,58 +3,44 @@
 /**
  * SEP-2164 Negative Test Server
  *
- * Returns an empty contents array for any resources/read request, violating
- * the SEP-2164 MUST NOT. The sep-2164-resource-not-found scenario should
- * emit FAILURE for sep-2164-no-empty-contents against this server.
+ * Speaks the stateless wire protocol (SEP-2575) but returns an empty
+ * contents array for any resources/read request, violating the SEP-2164 MUST
+ * NOT. The sep-2164-resource-not-found scenario should emit FAILURE for
+ * sep-2164-no-empty-contents against this server.
  */
 
-import { Server } from '@modelcontextprotocol/sdk/server/index.js';
-import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
-import {
-  ListResourcesRequestSchema,
-  ReadResourceRequestSchema
-} from '@modelcontextprotocol/sdk/types.js';
 import express from 'express';
 
-function createServer() {
-  const server = new Server(
-    { name: 'sep-2164-empty-contents', version: '1.0.0' },
-    { capabilities: { resources: {} } }
-  );
-
-  server.setRequestHandler(ListResourcesRequestSchema, async () => ({
-    resources: []
-  }));
-
-  server.setRequestHandler(ReadResourceRequestSchema, async () => ({
-    contents: []
-  }));
-
-  return server;
-}
-
 const app = express();
 app.use(express.json());
 
-app.post('/mcp', async (req, res) => {
-  try {
-    const server = createServer();
-    const transport = new StreamableHTTPServerTransport({
-      sessionIdGenerator: undefined
-    });
-    await server.connect(transport);
-    await transport.handleRequest(req, res, req.body);
-  } catch (error) {
-    if (!res.headersSent) {
-      res.status(500).json({
+app.post('/mcp', (req, res) => {
+  const body = req.body || {};
+  const id = body.id ?? null;
+  const method = body.method;
+
+  switch (method) {
+    case 'server/discover':
+      return res.json({
+        jsonrpc: '2.0',
+        id,
+        result: {
+          supportedVersions: ['DRAFT-2026-v1'],
+          capabilities: { resources: {} },
+          serverInfo: { name: 'sep-2164-empty-contents', version: '1.0.0' }
+        }
+      });
+    case 'resources/list':
+      return res.json({ jsonrpc: '2.0', id, result: { resources: [] } });
+    case 'resources/read':
+      // Deliberately return an empty contents array instead of an error.
+      return res.json({ jsonrpc: '2.0', id, result: { contents: [] } });
+    default:
+      return res.status(404).json({
         jsonrpc: '2.0',
-        error: {
-          code: -32603,
-          message: `Internal error: ${error instanceof Error ? error.message : String(error)}`
-        },
-        id: null
+        id,
+        error: { code: -32601, message: 'Method not found' }
       });
-    }
   }
 });