diff --git a/packages/plugins/mcp/src/sdk/discover-close.test.ts b/packages/plugins/mcp/src/sdk/discover-close.test.ts
new file mode 100644
index 000000000..89f8e78e3
--- /dev/null
+++ b/packages/plugins/mcp/src/sdk/discover-close.test.ts
@@ -0,0 +1,68 @@
+import { describe, expect, it } from "@effect/vitest";
+import { Effect } from "effect";
+
+import { createMcpConnector, type McpConnector } from "./connection";
+import { discoverTools } from "./discover";
+import { makeEchoMcpServer, serveMcpServer } from "../testing";
+
+// Exercise the real MCP handshake and catalog. The connector owns teardown,
+// so a wrapper can reproduce a transport that closes its sockets but never
+// settles its close promise without replacing the protocol client.
+const hangingCloseConnector = (connector: McpConnector, state: { closes: number }): McpConnector =>
+  Effect.map(connector, (connection) => ({
+    client: connection.client,
+    close: async () => {
+      state.closes += 1;
+      await connection.close();
+      return new Promise<void>(() => {});
+    },
+  }));
+
+describe("MCP discovery teardown", () => {
+  it.live("preserves a real catalog when close never settles", () =>
+    Effect.scoped(
+      Effect.gen(function* () {
+        const server = yield* serveMcpServer(() => makeEchoMcpServer({ name: "hanging-close" }));
+        const state = { closes: 0 };
+        const manifest = yield* discoverTools(
+          hangingCloseConnector(
+            createMcpConnector({
+              transport: "remote",
+              endpoint: server.url,
+              remoteTransport: "streamable-http",
+            }),
+            state,
+          ),
+        );
+        expect(state.closes).toBe(1);
+        expect(manifest.server?.name).toBe("hanging-close");
+        expect(manifest.tools.length).toBeGreaterThan(0);
+      }),
+    ),
+  );
+
+  it.live("preserves listing failure when close never settles", () =>
+    Effect.scoped(
+      Effect.gen(function* () {
+        const server = yield* serveMcpServer(() => makeEchoMcpServer());
+        yield* server.rejectSessionMethod("tools/list", 403);
+        const state = { closes: 0 };
+        const result = yield* discoverTools(
+          hangingCloseConnector(
+            createMcpConnector({
+              transport: "remote",
+              endpoint: server.url,
+              remoteTransport: "streamable-http",
+            }),
+            state,
+          ),
+        ).pipe(Effect.result);
+        expect(state.closes).toBe(1);
+        expect(result).toMatchObject({
+          _tag: "Failure",
+          failure: { stage: "list_tools", httpStatus: 403 },
+        });
+      }),
+    ),
+  );
+});
diff --git a/packages/plugins/mcp/src/sdk/discover.ts b/packages/plugins/mcp/src/sdk/discover.ts
index 754333eb3..d3c672361 100644
--- a/packages/plugins/mcp/src/sdk/discover.ts
+++ b/packages/plugins/mcp/src/sdk/discover.ts
@@ -31,6 +31,12 @@ const MAX_LIST_TOOLS_PAGES = 100;
 // shape probe's single unauth POST.
 const DEFAULT_DISCOVER_TIMEOUT = Duration.seconds(15);
 
+// Teardown is best-effort and paid for by the request that performed discovery.
+// A remote transport may accept close and then never settle, so use the same
+// bound as the invocation connection pool instead of stranding the caller in an
+// uninterruptible finalizer after discovery itself has already completed.
+const CLOSE_TIMEOUT = Duration.seconds(2);
+
 // ---------------------------------------------------------------------------
 // Public API
 // ---------------------------------------------------------------------------
@@ -243,13 +249,11 @@ export const discoverTools = (
 const closeConnection = (connection: {
   readonly close: () => Promise<void>;
 }): Effect.Effect<void, never> =>
-  Effect.ignore(
-    Effect.tryPromise({
-      try: () => connection.close(),
-      catch: () =>
-        new McpToolDiscoveryError({
-          stage: "list_tools",
-          message: "Failed closing MCP connection",
-        }),
-    }),
-  );
+  Effect.tryPromise({
+    try: () => connection.close(),
+    catch: () =>
+      new McpToolDiscoveryError({
+        stage: "list_tools",
+        message: "Failed closing MCP connection",
+      }),
+  }).pipe(Effect.timeout(CLOSE_TIMEOUT), Effect.ignore);