From 1782388547919c8f8f118b62148d12978b7a8bf5 Mon Sep 17 00:00:00 2001
From: Christian Bromann <git@bromann.dev>
Date: Fri, 14 Nov 2025 00:10:59 -0800
Subject: [PATCH] feat(anthropic): support websearch tool

---
 examples/src/provider/anthropic/websearch.ts  | 21 ++++++++++
 libs/langchain/tsconfig.json                  |  5 ++-
 .../langchain-anthropic/src/tools/index.ts    |  2 +
 .../src/tools/websearch.ts                    | 38 +++++++++++++++++++
 4 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 examples/src/provider/anthropic/websearch.ts
 create mode 100644 libs/providers/langchain-anthropic/src/tools/websearch.ts

diff --git a/examples/src/provider/anthropic/websearch.ts b/examples/src/provider/anthropic/websearch.ts
new file mode 100644
index 000000000000..c6fe80e77cfc
--- /dev/null
+++ b/examples/src/provider/anthropic/websearch.ts
@@ -0,0 +1,21 @@
+import { createAgent, HumanMessage } from "langchain";
+import { ChatAnthropic, tools } from "@langchain/anthropic";
+
+const model = new ChatAnthropic({
+  model: "claude-sonnet-4-5-20250929",
+});
+
+const agent = createAgent({
+  model,
+  tools: [
+    tools.webSearch_20250305({
+      maxUses: 5,
+    }),
+  ],
+});
+
+const result = await agent.invoke({
+  messages: [new HumanMessage("What's the weather in NYC?")],
+});
+
+console.log(result);
diff --git a/libs/langchain/tsconfig.json b/libs/langchain/tsconfig.json
index 8c69a82c22c2..e9b3a2f2bf90 100644
--- a/libs/langchain/tsconfig.json
+++ b/libs/langchain/tsconfig.json
@@ -18,6 +18,9 @@
     "allowJs": true,
     "strict": true
   },
-  "include": ["src/**/*"],
+  "include": [
+    "src/**/*",
+    "../providers/langchain-anthropic/src/tools/utils/FileData.ts"
+  ],
   "exclude": ["node_modules", "dist", "docs"]
 }
diff --git a/libs/providers/langchain-anthropic/src/tools/index.ts b/libs/providers/langchain-anthropic/src/tools/index.ts
index de9cd54bd038..9c15c493fd83 100644
--- a/libs/providers/langchain-anthropic/src/tools/index.ts
+++ b/libs/providers/langchain-anthropic/src/tools/index.ts
@@ -1,4 +1,5 @@
 import { memory, memory_20250818 } from "./memory.js";
+import { webSearch_20250305 } from "./websearch.js";
 
 export type { FileSystem } from "./utils/FileSystem.js";
 export { StateFileSystem } from "./utils/StateFileSystem.js";
@@ -6,4 +7,5 @@ export { StateFileSystem } from "./utils/StateFileSystem.js";
 export const tools = {
   memory_20250818,
   memory,
+  webSearch_20250305,
 };
diff --git a/libs/providers/langchain-anthropic/src/tools/websearch.ts b/libs/providers/langchain-anthropic/src/tools/websearch.ts
new file mode 100644
index 000000000000..ef500c885bd7
--- /dev/null
+++ b/libs/providers/langchain-anthropic/src/tools/websearch.ts
@@ -0,0 +1,38 @@
+import Anthropic from "@anthropic-ai/sdk";
+
+import { tool, type DynamicStructuredTool } from "@langchain/core/tools";
+
+interface WebSearchOptions {
+  maxUses?: number;
+  allowedDomains?: string[];
+  blockedDomains?: string[];
+  userLocation?: Anthropic.Beta.BetaWebSearchTool20250305.UserLocation;
+}
+
+export function webSearch_20250305(
+  options?: WebSearchOptions
+): DynamicStructuredTool {
+  const webSearchTool = tool(
+    () => {
+      // not implemented
+    },
+    {
+      name: "web_search",
+      description: "Web search tool",
+      schema: {},
+    }
+  );
+
+  webSearchTool.metadata = {
+    providerToolDefinition: {
+      type: "web_search_20250305",
+      name: "web_search",
+      max_uses: options?.maxUses,
+      allowed_domains: options?.allowedDomains,
+      blocked_domains: options?.blockedDomains,
+      user_location: options?.userLocation,
+    },
+  };
+
+  return webSearchTool;
+}