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..6550cac9da1 100644
--- a/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
+++ b/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
@@ -1,4 +1,4 @@
-from collections.abc import AsyncIterator
+from collections.abc import AsyncIterator, Mapping
 from typing import TYPE_CHECKING, Any, Final, cast
 
 import httpx
@@ -56,6 +56,9 @@ else:
     LiteLLMLoggingObj = Any
 
 
+UNSUPPORTED_BEDROCK_SERVER_TOOL_PREFIX: Final = "web_search_"
+
+
 class AmazonAnthropicClaudeMessagesConfig(
     AnthropicMessagesConfig,
     AmazonInvokeConfig,
@@ -605,6 +608,39 @@ class AmazonAnthropicClaudeMessagesConfig(
         normalize_bedrock_opus_output_config_effort(model=model, output_config=clamped)
         optional_params["reasoning_effort"] = clamped["effort"]
 
+    def _reject_unsupported_server_tools(self, anthropic_messages_request: Mapping[str, object], model: str) -> None:
+        """Bedrock hosts none of Anthropic's ``web_search_*`` server tools, so
+        forwarding one earns an opaque ``The provided request is not valid`` from
+        AWS that names neither the tool nor a way forward. Web-search
+        interception rewrites the tool before this point, so reaching here means
+        it is not configured for this request.
+        """
+        tools: Final = anthropic_messages_request.get("tools")
+        if not isinstance(tools, list):
+            return
+        entries: Final = cast(list[Mapping[str, object]], tools)  # cast-ok: request body is untyped upstream
+        unsupported: Final = sorted(
+            {
+                tool_type
+                for tool in entries
+                if isinstance(tool_type := tool.get("type"), str)
+                if tool_type.startswith(UNSUPPORTED_BEDROCK_SERVER_TOOL_PREFIX)
+            }
+        )
+        if not unsupported:
+            return
+        raise litellm.BadRequestError(
+            message=(
+                f"Amazon Bedrock does not support the Anthropic server tool(s) {unsupported}. "
+                "Enable LiteLLM's web-search interception to serve them, by adding "
+                '`websearch_interception` to `litellm_settings.callbacks`, listing "bedrock" under '
+                "`litellm_settings.websearch_interception_params.enabled_providers`, and declaring a "
+                "`search_tools` entry. Otherwise remove the tool from the request."
+            ),
+            model=model,
+            llm_provider="bedrock",
+        )
+
     def transform_anthropic_messages_request(
         self,
         model: str,
@@ -626,6 +662,8 @@ class AmazonAnthropicClaudeMessagesConfig(
             headers=headers,
         )
         self._normalize_system_role_messages(anthropic_messages_request, model=model)
+        request_view: Final = cast(Mapping[str, object], anthropic_messages_request)  # cast-ok: body is untyped here
+        self._reject_unsupported_server_tools(request_view, model=model)
         #########################################################
         ############## BEDROCK Invoke SPECIFIC TRANSFORMATION ###
         #########################################################
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..d0dc5fcb804 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
@@ -29,6 +29,8 @@ from litellm.llms.bedrock.messages.invoke_transformations.anthropic_claude3_tran
     AmazonAnthropicClaudeMessagesConfig,
     AmazonAnthropicClaudeMessagesStreamDecoder,
 )
+import litellm
+from litellm.types.router import GenericLiteLLMParams
 
 
 @pytest.fixture
@@ -2580,3 +2582,50 @@ 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
+
+
+def test_bedrock_messages_rejects_anthropic_web_search_server_tool():
+    """Bedrock hosts none of Anthropic's web_search server tools. Forwarding one
+    earns an opaque 'The provided request is not valid' from AWS that names
+    neither the tool nor a way forward, so reject it here with a message that
+    does both."""
+    with pytest.raises(litellm.BadRequestError) as excinfo:
+        AmazonAnthropicClaudeMessagesConfig().transform_anthropic_messages_request(
+            model="us.anthropic.claude-haiku-4-5-20251001-v1:0",
+            messages=[{"role": "user", "content": "Anthropic Claude news"}],
+            anthropic_messages_optional_request_params={
+                "max_tokens": 64,
+                "tools": [{"type": "web_search_20250305", "name": "web_search", "max_uses": 3}],
+            },
+            litellm_params=GenericLiteLLMParams(),
+            headers={},
+        )
+
+    message = str(excinfo.value)
+    assert "web_search_20250305" in message
+    assert "websearch_interception" in message
+
+
+def test_bedrock_messages_allows_the_tool_interception_rewrites_it_into():
+    """Web-search interception rewrites the native tool into LiteLLM's own search
+    tool before this transform runs, and that rewritten tool carries an
+    input_schema like any custom tool. Rejecting the native type must not touch
+    it, or enabling interception would break the very path that serves search."""
+    body = AmazonAnthropicClaudeMessagesConfig().transform_anthropic_messages_request(
+        model="us.anthropic.claude-haiku-4-5-20251001-v1:0",
+        messages=[{"role": "user", "content": "Anthropic Claude news"}],
+        anthropic_messages_optional_request_params={
+            "max_tokens": 64,
+            "tools": [
+                {
+                    "name": "litellm_web_search",
+                    "description": "Search the web",
+                    "input_schema": {"type": "object", "properties": {"query": {"type": "string"}}},
+                }
+            ],
+        },
+        litellm_params=GenericLiteLLMParams(),
+        headers={},
+    )
+
+    assert [tool["name"] for tool in body["tools"]] == ["litellm_web_search"]