Wait briefly for connecting servers before answering an empty tool search

A search that misses while a connector handshake is still in flight now waits briefly for the handshake, then reports the miss as possibly incomplete instead of definitive.

Author: TheGreatAxios

src/agent/tool-search.test.ts

@@ -317,6 +317,38 @@ describe("createToolSearchTool", () => {
     expect(out).toContain("mcp__linear__create_issue");
     expect(out).not.toContain("No tools matched");
   });
+
+  test("a hung connection never hangs the search — bounded wait, then a retry signal", async () => {
+    const tool = createToolSearchTool({
+      search: () => [],
+      lookup: () => undefined,
+      promote: () => undefined,
+      awaitPendingConnections: () =>
+        new Promise<number>(() => {
+          // Never settles: simulates a hung authorization handshake.
+        }),
+    });
+    const out = await call(tool, { query: "linear" });
+    expect(out).toContain("No tools matched");
+    expect(out).toMatch(/starting up|still connecting/);
+    expect(out).toMatch(/retry.*shortly/i);
+    expect(out).not.toContain("different keywords");
+  });
+
+  test("a genuine miss keeps the keyword advice and omits the retry caveat", async () => {
+    const tool = createToolSearchTool({
+      search: () => [],
+      lookup: () => undefined,
+      promote: () => undefined,
+      awaitPendingConnections: async () => 0,
+    });
+    const out = await call(tool, { query: "nonsense" });
+    expect(out).toContain("No tools matched");
+    expect(out).toContain("different keywords");
+    expect(out).not.toMatch(
+      /still connecting|still starting up|retry shortly/i,
+    );
+  });
 });
 
 describe("advertisedTools", () => {

src/agent/tool-search.ts

@@ -283,8 +283,18 @@ export interface ToolSearchDeps {
   // invoke them this turn. The next inference also declares them on the wire
   // for strict providers.
   promote: (names: string[]) => void;
+  // Resolves to the remaining in-flight MCP handshake count after waiting up
+  // to `timeoutMs`. The toolset bounds its own wait; the handler re-races
+  // below so even a stuck dependency can never hang the call. Omitted callers
+  // (tests, ad-hoc indexes) have no pending handshakes to wait for.
+  awaitPendingConnections?: (timeoutMs?: number) => Promise<number>;
 }
 
+// Brief bound a tool_search miss waits for in-flight MCP handshakes before
+// answering. A hung authorization must never hang the call, so both the
+// toolset wait and the handler race below are capped by this.
+export const TOOL_SEARCH_PENDING_WAIT_MS = 1_000;
+
 const ToolSearchArgs = type({ query: "string" });
 
 // Render one discovered tool as name, description, and pretty-printed input
@@ -305,6 +315,28 @@ function indent(text: string, pad: string): string {
     .join("\n");
 }
 
+// Race the dependency's pending-count wait against the same bound, so a
+// stuck dependency (hung OAuth that never settles) cannot hang the call.
+// Resolves undefined when this race itself times out.
+async function racePendingCount(
+  awaitPending: (timeoutMs?: number) => Promise<number>,
+): Promise<number | undefined> {
+  let timer: ReturnType<typeof setTimeout> | undefined;
+  try {
+    return await Promise.race([
+      awaitPending(TOOL_SEARCH_PENDING_WAIT_MS),
+      new Promise<undefined>((resolve) => {
+        timer = setTimeout(
+          () => resolve(undefined),
+          TOOL_SEARCH_PENDING_WAIT_MS,
+        );
+      }),
+    ]);
+  } finally {
+    if (timer !== undefined) clearTimeout(timer);
+  }
+}
+
 export function createToolSearchTool(deps: ToolSearchDeps): AgentTool {
   return stringTool({
     definition: toolSearchDefinition,
@@ -316,7 +348,25 @@ export function createToolSearchTool(deps: ToolSearchDeps): AgentTool {
       const query = parsed.query.trim();
       if (query.length === 0)
         return "Error: tool_search requires a non-empty query.";
-      const names = deps.search(query);
+      let names = deps.search(query);
+      if (names.length === 0 && deps.awaitPendingConnections !== undefined) {
+        // Miss while connectors start up: wait briefly, then re-search so
+        // late-mounting tools land. The race bounds even a stuck dependency
+        // (hung OAuth) — undefined means the wait itself timed out.
+        const stillPending = await racePendingCount(
+          deps.awaitPendingConnections,
+        );
+        names = deps.search(query);
+        if (names.length === 0 && (stillPending ?? 1) > 0) {
+          const detail =
+            stillPending === undefined
+              ? "a connector may still be starting up"
+              : stillPending === 1
+                ? "1 connector is still connecting"
+                : `${stillPending} connectors are still connecting`;
+          return `No tools matched "${query}" yet — ${detail}. Retry this search shortly.`;
+        }
+      }
       if (names.length === 0) {
         return `No tools matched "${query}". Try different keywords describing the capability.`;
       }

src/agent/tools.ts

@@ -103,7 +103,11 @@ import {
 } from "../tools/web-search.js";
 import { createUseSkillTool } from "./use-skill.js";
 import { createSkillSearchTool } from "./skill-search.js";
-import { createToolIndex, createToolSearchTool } from "./tool-search.js";
+import {
+  createToolIndex,
+  createToolSearchTool,
+  TOOL_SEARCH_PENDING_WAIT_MS,
+} from "./tool-search.js";
 import { createSearchAgentsTool } from "./agent-search.js";
 import { createReadAgentTraceTool } from "../subagent/trace-tool.js";
 import {
@@ -319,6 +323,14 @@ export interface AgentToolset {
   // second add of an active name; failed rows retry through connectMCPServer
   // without a second persist. Still true while disable is in progress.
   hasMCPServer: (name: string) => boolean;
+  // Live MCP handshake depth: non-zero while any server is still connecting.
+  // tool_search consults this on a miss — waiting briefly and reporting a
+  // retry signal instead of a definitive negative mid-handshake.
+  pendingMcpConnectionCount: () => number;
+  // Bounded wait for in-flight MCP handshakes; resolves to the remaining
+  // count. Capped by `timeoutMs` so a hung authorization never hangs the
+  // caller — the tool_search bound passes briefly by default.
+  awaitPendingMcpConnections: (timeoutMs?: number) => Promise<number>;
   // Catalog unshadow can change local → global/none without rebuilding the
   // toolset; connectOne reads this on every late connect.
   setMcpServersSource: (source: "local" | "global" | "none") => void;
@@ -719,6 +731,12 @@ export async function createAgentToolset(
       lookup: (name) =>
         runnerHolder.current?.currentDefinitions().find((d) => d.name === name),
       promote: (names) => promoter.promote(names),
+      // Misses wait briefly for in-flight MCP handshakes (bounded, so hung
+      // OAuth cannot hang the call) and re-search before answering. Reads the
+      // connection map live — declared below, populated by the time any
+      // search runs.
+      awaitPendingConnections: (timeoutMs = TOOL_SEARCH_PENDING_WAIT_MS) =>
+        awaitPendingMcpConnections(timeoutMs),
     }),
   );
 
@@ -744,6 +762,30 @@ export async function createAgentToolset(
   const connectedClients = new Map<string, MCPClient>();
   const inFlightConnections = new Map<string, Promise<void>>();
   const inFlightEpochs = new Map<string, number>();
+  // Live handshake depth for tool_search: a miss waits briefly for these
+  // before answering, so a mid-handshake search finds late-mounting tools
+  // instead of reporting a definitive negative.
+  const pendingMcpConnectionCount = (): number => inFlightConnections.size;
+  // Bounded wait for in-flight handshakes; resolves to the remaining count.
+  // Capped by `timeoutMs` so a hung authorization never hangs the caller.
+  const awaitPendingMcpConnections = async (
+    timeoutMs = TOOL_SEARCH_PENDING_WAIT_MS,
+  ): Promise<number> => {
+    if (inFlightConnections.size === 0) return 0;
+    const pending = [...inFlightConnections.values()];
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    try {
+      await Promise.race([
+        Promise.allSettled(pending),
+        new Promise<void>((resolve) => {
+          timer = setTimeout(resolve, timeoutMs);
+        }),
+      ]);
+    } finally {
+      if (timer !== undefined) clearTimeout(timer);
+    }
+    return inFlightConnections.size;
+  };
   const disabledNames = new Set<string>();
   const serverAborts = new Map<string, AbortController>();
   const serverEpochs = new Map<string, number>();
@@ -1218,6 +1260,8 @@ export async function createAgentToolset(
     disconnectMCPServer: publicDisconnectMCPServer,
     hasMCPServer: (name) =>
       connectedClients.has(name) || inFlightConnections.has(name),
+    pendingMcpConnectionCount,
+    awaitPendingMcpConnections,
     setMcpServersSource: (source) => {
       mcpServersSource = source;
     },