diff --git a/src/agents/tools/web-fetch.ts b/src/agents/tools/web-fetch.ts
index c6e19046fde7..bc7f8011c36f 100644
--- a/src/agents/tools/web-fetch.ts
+++ b/src/agents/tools/web-fetch.ts
@@ -15,7 +15,7 @@ import { extractReadableContent } from "../../web-fetch/content-extractors.runti
 import { resolveWebProviderConfig } from "../../web/provider-runtime-shared.js";
 import { stringEnum } from "../schema/string-enum.js";
 import type { AnyAgentTool } from "./common.js";
-import { jsonResult, readNumberParam, readStringParam } from "./common.js";
+import { jsonResult, readPositiveIntegerParam, readStringParam } from "./common.js";
 import {
   extractBasicHtmlContent,
   htmlToMarkdown,
@@ -59,7 +59,7 @@ const WebFetchSchema = Type.Object({
     }),
   ),
   maxChars: Type.Optional(
-    Type.Number({
+    Type.Integer({
       description: "Max chars returned; truncates.",
       minimum: 100,
     }),
@@ -674,7 +674,7 @@ export function createWebFetchTool(options?: {
       const params = args as Record<string, unknown>;
       const url = readStringParam(params, "url", { required: true });
       const extractMode = readStringParam(params, "extractMode") === "text" ? "text" : "markdown";
-      const maxChars = readNumberParam(params, "maxChars", { integer: true });
+      const maxChars = readPositiveIntegerParam(params, "maxChars");
       const maxCharsCap = resolveFetchMaxCharsCap(executionFetch);
       const result = await runWebFetch({
         url,
diff --git a/src/agents/tools/web-tools.fetch.test.ts b/src/agents/tools/web-tools.fetch.test.ts
index f48d319b4106..09f926a24857 100644
--- a/src/agents/tools/web-tools.fetch.test.ts
+++ b/src/agents/tools/web-tools.fetch.test.ts
@@ -534,6 +534,23 @@ describe("web_fetch extraction fallbacks", () => {
     expect(details.truncated).toBe(true);
   });
 
+  it("rejects fractional maxChars before fetching", async () => {
+    const fetchMock = installMockFetch(
+      (input: RequestInfo | URL) =>
+        Promise.resolve(textResponse("unused", resolveRequestUrl(input))) as Promise<Response>,
+    );
+
+    const tool = createFetchTool({ firecrawl: { enabled: false } });
+
+    await expect(
+      tool?.execute?.("call", {
+        url: "https://example.com/fractional",
+        maxChars: 100.5,
+      }),
+    ).rejects.toThrow("maxChars must be a positive integer");
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+
   it("strips and truncates HTML from error responses", async () => {
     const long = "x".repeat(12_000);
     const html =