fix(mcp): preserve metadata across tool pages (#35439)

packages/opencode/test/mcp/catalog.test.ts

@@ -1,6 +1,10 @@
 import { describe, expect, test } from "bun:test"
-import type { Client } from "@modelcontextprotocol/sdk/client/index.js"
+import { Client } from "@modelcontextprotocol/sdk/client/index.js"
+import { InMemoryTransport } from "@modelcontextprotocol/sdk/inMemory.js"
+import { Server } from "@modelcontextprotocol/sdk/server/index.js"
+import { CallToolRequestSchema, ListToolsRequestSchema } from "@modelcontextprotocol/sdk/types.js"
 import { McpCatalog } from "@/mcp/catalog"
+import { Effect } from "effect"
 
 const options = { toolCallId: "call_mcp", abortSignal: new AbortController().signal } as any
 
@@ -45,3 +49,59 @@ describe("McpCatalog.convertTool", () => {
     })
   })
 })
+
+test("preserves output schema validation across paginated tool discovery", async () => {
+  const server = new Server({ name: "pagination", version: "1.0.0" }, { capabilities: { tools: {} } })
+  server.setRequestHandler(ListToolsRequestSchema, ({ params }) =>
+    Promise.resolve(
+      params?.cursor === "page-2"
+        ? {
+            tools: [
+              {
+                name: "second",
+                inputSchema: { type: "object" },
+                outputSchema: {
+                  type: "object",
+                  properties: { value: { type: "number" } },
+                  required: ["value"],
+                },
+              },
+            ],
+          }
+        : {
+            tools: [
+              {
+                name: "first",
+                inputSchema: { type: "object" },
+                outputSchema: {
+                  type: "object",
+                  properties: { value: { type: "string" } },
+                  required: ["value"],
+                },
+              },
+            ],
+            nextCursor: "page-2",
+          },
+    ),
+  )
+  server.setRequestHandler(CallToolRequestSchema, ({ params }) =>
+    Promise.resolve({
+      content: [],
+      structuredContent: { value: params.name === "first" ? 42 : 1 },
+    }),
+  )
+
+  const client = new Client({ name: "pagination-test", version: "1.0.0" })
+  const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair()
+  await Promise.all([client.connect(clientTransport), server.connect(serverTransport)])
+
+  try {
+    const tools = await Effect.runPromise(McpCatalog.defs(client))
+    expect(tools?.map((tool) => tool.name)).toEqual(["first", "second"])
+    await expect(client.callTool({ name: "first", arguments: {} })).rejects.toThrow(
+      "Structured content does not match the tool's output schema",
+    )
+  } finally {
+    await Promise.all([client.close(), server.close()])
+  }
+})