diff --git a/src/agents/tools/web-search.test.ts b/src/agents/tools/web-search.test.ts
index 31069d23657..cb6ed3fe124 100644
--- a/src/agents/tools/web-search.test.ts
+++ b/src/agents/tools/web-search.test.ts
@@ -1,11 +1,24 @@
 import { describe, expect, it } from "vitest";
 import {
+  MAX_SEARCH_COUNT,
   buildUnsupportedSearchFilterResponse,
   isoToPerplexityDate,
   normalizeToIsoDate,
   normalizeFreshness,
 } from "./web-search-provider-common.js";
 import { mergeScopedSearchConfig } from "./web-search-provider-config.js";
+import { createWebSearchTool } from "./web-search.js";
+
+describe("web_search tool schema", () => {
+  it("advertises the shared runtime count limit", () => {
+    const tool = createWebSearchTool();
+    const parameters = tool?.parameters as
+      | { properties?: { count?: { maximum?: unknown } } }
+      | undefined;
+
+    expect(parameters?.properties?.count?.maximum).toBe(MAX_SEARCH_COUNT);
+  });
+});
 
 describe("web_search freshness normalization", () => {
   it("accepts Brave shortcut values and maps for Perplexity", () => {
diff --git a/src/agents/tools/web-search.ts b/src/agents/tools/web-search.ts
index 789b24dda2a..4a3565e2e40 100644
--- a/src/agents/tools/web-search.ts
+++ b/src/agents/tools/web-search.ts
@@ -4,7 +4,7 @@ import type { RuntimeWebSearchMetadata } from "../../secrets/runtime-web-tools.t
 import { resolveWebSearchProviderId, runWebSearch } from "../../web-search/runtime.js";
 import type { AnyAgentTool } from "./common.js";
 import { asToolParamsRecord, jsonResult } from "./common.js";
-import { SEARCH_CACHE } from "./web-search-provider-common.js";
+import { MAX_SEARCH_COUNT, SEARCH_CACHE } from "./web-search-provider-common.js";
 
 const WebSearchSchema = {
   type: "object",
@@ -14,7 +14,7 @@ const WebSearchSchema = {
       type: "number",
       description: "Number of results to return.",
       minimum: 1,
-      maximum: 20,
+      maximum: MAX_SEARCH_COUNT,
     },
     country: {
       type: "string",