Add MCP executeTool server-selection regression tests

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

src/agent/mcp/client.test.ts

@@ -1,4 +1,4 @@
-import { normalizeMCPToolParams } from "@/agent/mcp/client";
+import { MCPClient, normalizeMCPToolParams } from "@/agent/mcp/client";
 
 describe("normalizeMCPToolParams", () => {
   it("returns object inputs unchanged", () => {
@@ -26,3 +26,105 @@ describe("normalizeMCPToolParams", () => {
     );
   });
 });
+
+describe("MCPClient.executeTool server selection", () => {
+  function setServers(
+    client: MCPClient,
+    servers: Map<
+      string,
+      {
+        tools: Map<string, unknown>;
+        client: { callTool: jest.Mock };
+      }
+    >
+  ): void {
+    (
+      client as unknown as {
+        servers: Map<
+          string,
+          {
+            tools: Map<string, unknown>;
+            client: { callTool: jest.Mock };
+          }
+        >;
+      }
+    ).servers = servers;
+  }
+
+  it("uses the only connected server when serverId is omitted", async () => {
+    const mcpClient = new MCPClient(false);
+    const callTool = jest.fn().mockResolvedValue({ content: [] });
+    setServers(
+      mcpClient,
+      new Map([
+        [
+          "server-1",
+          {
+            tools: new Map([["search", {}]]),
+            client: { callTool },
+          },
+        ],
+      ])
+    );
+
+    await mcpClient.executeTool("search", { query: "weather" });
+
+    expect(callTool).toHaveBeenCalledWith({
+      name: "search",
+      arguments: { query: "weather" },
+    });
+  });
+
+  it("finds matching server by tool name when multiple are connected", async () => {
+    const mcpClient = new MCPClient(false);
+    const searchCallTool = jest.fn().mockResolvedValue({ content: [] });
+    const notesCallTool = jest.fn().mockResolvedValue({ content: [] });
+    setServers(
+      mcpClient,
+      new Map([
+        [
+          "server-a",
+          {
+            tools: new Map([["notes", {}]]),
+            client: { callTool: notesCallTool },
+          },
+        ],
+        [
+          "server-b",
+          {
+            tools: new Map([["search", {}]]),
+            client: { callTool: searchCallTool },
+          },
+        ],
+      ])
+    );
+
+    await mcpClient.executeTool("search", { query: "coffee" });
+
+    expect(searchCallTool).toHaveBeenCalledWith({
+      name: "search",
+      arguments: { query: "coffee" },
+    });
+    expect(notesCallTool).not.toHaveBeenCalled();
+  });
+
+  it("throws when provided serverId does not exist", async () => {
+    const mcpClient = new MCPClient(false);
+    setServers(
+      mcpClient,
+      new Map([
+        [
+          "server-a",
+          {
+            tools: new Map([["notes", {}]]),
+            client: { callTool: jest.fn() },
+          },
+        ],
+      ])
+    );
+
+    await expect(
+      mcpClient.executeTool("search", { query: "missing" }, "unknown-server")
+    ).rejects.toThrow("No valid server found for tool search");
+  });
+});