diff --git a/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py b/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
index 85fda3a6522..fad7e7558c2 100644
--- a/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
+++ b/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
@@ -67,6 +67,8 @@ class AmazonAnthropicClaudeMessagesConfig(
 
     DEFAULT_BEDROCK_ANTHROPIC_API_VERSION = "bedrock-2023-05-31"
 
+    WEBSEARCH_INTERCEPTION_DOCS_URL = "https://docs.litellm.ai/docs/integrations/websearch_interception"
+
     @property
     def custom_llm_provider(self) -> str | None:
         return "bedrock"
@@ -572,6 +574,45 @@ class AmazonAnthropicClaudeMessagesConfig(
 
         return filtered_betas
 
+    @staticmethod
+    def _reject_unsupported_web_search_tools(anthropic_messages_request: dict[str, object], model: str) -> None:
+        """
+        Bedrock's Anthropic endpoints cannot execute Anthropic's server-side
+        ``web_search_*`` tool; forwarding it returns an opaque
+        "The provided request is not valid" 400 from Bedrock. Fail fast with an
+        error that names the problem and the fix instead.
+
+        When web search interception is enabled
+        (``litellm_settings.callbacks: ["websearch_interception"]``), the tool
+        is converted to a regular function tool before this transform runs, so
+        this guard never fires.
+        """
+        from litellm.integrations.websearch_interception.tools import (
+            is_anthropic_native_web_search_tool,
+        )
+
+        tools: Final = anthropic_messages_request.get("tools")
+        if not isinstance(tools, list):
+            return
+        web_search_tool: Final = next(
+            (t for t in tools if isinstance(t, dict) and is_anthropic_native_web_search_tool(t)),
+            None,
+        )
+        if web_search_tool is None:
+            return
+        raise litellm.BadRequestError(
+            message=(
+                f"Bedrock does not support Anthropic's server-side web search tool "
+                f"(tool type '{web_search_tool.get('type')}', model '{model}'). "
+                "To use web search with this model, enable LiteLLM's web search interception "
+                "so the proxy executes the search instead: "
+                f"{AmazonAnthropicClaudeMessagesConfig.WEBSEARCH_INTERCEPTION_DOCS_URL}. "
+                "Alternatively, remove the web_search tool from the request."
+            ),
+            model=model,
+            llm_provider="bedrock",
+        )
+
     def _strip_unsupported_bedrock_invoke_fields(
         self,
         anthropic_messages_request: dict,
@@ -630,6 +671,8 @@ class AmazonAnthropicClaudeMessagesConfig(
         ############## BEDROCK Invoke SPECIFIC TRANSFORMATION ###
         #########################################################
 
+        self._reject_unsupported_web_search_tools(anthropic_messages_request=anthropic_messages_request, model=model)
+
         # 1. anthropic_version is required for all claude models
         if "anthropic_version" not in anthropic_messages_request:
             anthropic_messages_request["anthropic_version"] = self.DEFAULT_BEDROCK_ANTHROPIC_API_VERSION
diff --git a/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py b/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py
index 76bb11cc26d..2d1a5bc4c2a 100644
--- a/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py
+++ b/tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py
@@ -2580,3 +2580,52 @@ def test_replayed_intercepted_search_turn_leaves_no_unsupported_block_for_bedroc
     assert "server_tool_use" not in serialized
     assert expected_evidence in serialized
     assert "Rome was founded in 753 BC." in serialized
+
+
+@pytest.mark.parametrize("tool_type", ["web_search_20250305", "web_search_20260209"])
+def test_bedrock_invoke_messages_rejects_server_web_search_tool(tool_type: str):
+    """Bedrock can't execute Anthropic's server-side web search; the transform
+    must raise an actionable 400 pointing at the interception docs instead of
+    letting Bedrock return an opaque "provided request is not valid"."""
+    import litellm
+    from litellm.types.router import GenericLiteLLMParams
+
+    cfg = AmazonAnthropicClaudeMessagesConfig()
+    with pytest.raises(litellm.BadRequestError) as exc_info:
+        cfg.transform_anthropic_messages_request(
+            model="us.anthropic.claude-haiku-4-5-20251001-v1:0",
+            messages=[{"role": "user", "content": "search the web for litellm"}],
+            anthropic_messages_optional_request_params={
+                "max_tokens": 128,
+                "tools": [{"type": tool_type, "name": "web_search", "max_uses": 5}],
+            },
+            litellm_params=GenericLiteLLMParams(),
+            headers={},
+        )
+    assert "https://docs.litellm.ai/docs/integrations/websearch_interception" in str(exc_info.value)
+    assert "us.anthropic.claude-haiku-4-5-20251001-v1:0" in str(exc_info.value)
+
+
+def test_bedrock_invoke_messages_allows_converted_websearch_function_tool():
+    """The interception hook rewrites web_search into a plain custom tool
+    (litellm_web_search); that converted shape must pass through untouched."""
+    from litellm.types.router import GenericLiteLLMParams
+
+    cfg = AmazonAnthropicClaudeMessagesConfig()
+    result = cfg.transform_anthropic_messages_request(
+        model="us.anthropic.claude-haiku-4-5-20251001-v1:0",
+        messages=[{"role": "user", "content": "search the web for litellm"}],
+        anthropic_messages_optional_request_params={
+            "max_tokens": 128,
+            "tools": [
+                {
+                    "name": "litellm_web_search",
+                    "description": "Search the web",
+                    "input_schema": {"type": "object", "properties": {"query": {"type": "string"}}},
+                }
+            ],
+        },
+        litellm_params=GenericLiteLLMParams(),
+        headers={},
+    )
+    assert result["tools"][0]["name"] == "litellm_web_search"