fix(bedrock): filter out custom field from tools to prevent 400 errors (#22861)

Claude Code v2.1.69+ sends `custom: {defer_loading: true}` on tool
definitions. Anthropic's API accepts this field, but Bedrock rejects it
with "Extra inputs are not permitted", causing ~90% of requests to fail.

Strip the `custom` field from each tool in the request body before
sending to Bedrock, in both the Messages API and Chat API invoke paths.

Fixes #22847

Co-authored-by: Ishaan Jaff <ishaanjaffer0324@gmail.com>

litellm/llms/bedrock/chat/invoke_transformations/anthropic_claude3_transformation.py

@@ -6,7 +6,10 @@ from litellm.llms.anthropic.chat.transformation import AnthropicConfig
 from litellm.llms.bedrock.chat.invoke_transformations.base_invoke_transformation import (
     AmazonInvokeConfig,
 )
-from litellm.llms.bedrock.common_utils import get_anthropic_beta_from_headers
+from litellm.llms.bedrock.common_utils import (
+    get_anthropic_beta_from_headers,
+    remove_custom_field_from_tools,
+)
 from litellm.types.llms.anthropic import ANTHROPIC_TOOL_SEARCH_BETA_HEADER
 from litellm.types.llms.openai import AllMessageValues
 from litellm.types.utils import ModelResponse
@@ -108,6 +111,12 @@ class AmazonAnthropicClaudeConfig(AmazonInvokeConfig, AnthropicConfig):
         if "anthropic_version" not in _anthropic_request:
             _anthropic_request["anthropic_version"] = self.anthropic_version
 
+        # Remove `custom` field from tools (Bedrock doesn't support it)
+        # Claude Code sends `custom: {defer_loading: true}` on tool definitions,
+        # which causes Bedrock to reject the request with "Extra inputs are not permitted"
+        # Ref: https://github.com/BerriAI/litellm/issues/22847
+        remove_custom_field_from_tools(_anthropic_request)
+
         tools = optional_params.get("tools")
         tool_search_used = self.is_tool_search_used(tools)
         programmatic_tool_calling_used = self.is_programmatic_tool_calling_used(tools)

litellm/llms/bedrock/common_utils.py

@@ -49,6 +49,27 @@ def get_cached_model_info():
     return _get_model_info
 
 
+def remove_custom_field_from_tools(request_body: dict) -> None:
+    """
+    Remove ``custom`` field from each tool in the request body.
+
+    Claude Code (v2.1.69+) sends ``custom: {defer_loading: true}`` on tool
+    definitions, which Anthropic's API accepts but Bedrock rejects with
+    ``"Extra inputs are not permitted"``.
+
+    Args:
+        request_body: The request dictionary to modify in-place.
+
+    Ref: https://github.com/BerriAI/litellm/issues/22847
+    """
+    tools = request_body.get("tools")
+    if not tools or not isinstance(tools, list):
+        return
+    for tool in tools:
+        if isinstance(tool, dict):
+            tool.pop("custom", None)
+
+
 class AmazonBedrockGlobalConfig:
     def __init__(self):
         pass

litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py

@@ -26,6 +26,7 @@ from litellm.llms.bedrock.chat.invoke_transformations.base_invoke_transformation
 from litellm.llms.bedrock.common_utils import (
     get_anthropic_beta_from_headers,
     is_claude_4_5_on_bedrock,
+    remove_custom_field_from_tools,
 )
 from litellm.types.llms.anthropic import ANTHROPIC_TOOL_SEARCH_BETA_HEADER
 from litellm.types.llms.openai import AllMessageValues
@@ -402,6 +403,12 @@ class AmazonAnthropicClaudeMessagesConfig(
                 anthropic_messages_request=anthropic_messages_request,
             )
 
+        # 5a. Remove `custom` field from tools (Bedrock doesn't support it)
+        # Claude Code sends `custom: {defer_loading: true}` on tool definitions,
+        # which causes Bedrock to reject the request with "Extra inputs are not permitted"
+        # Ref: https://github.com/BerriAI/litellm/issues/22847
+        remove_custom_field_from_tools(anthropic_messages_request)
+
         # 6. AUTO-INJECT beta headers based on features used
         anthropic_model_info = AnthropicModelInfo()
         tools = anthropic_messages_optional_request_params.get("tools")

tests/test_litellm/llms/bedrock/messages/invoke_transformations/test_anthropic_claude3_transformation.py

@@ -11,6 +11,7 @@ import pytest
 sys.path.insert(0, os.path.abspath("../../../../../.."))
 
 from litellm.litellm_core_utils.litellm_logging import Logging as LiteLLMLoggingObj
+from litellm.llms.bedrock.common_utils import remove_custom_field_from_tools
 from litellm.llms.bedrock.messages.invoke_transformations.anthropic_claude3_transformation import (
     AmazonAnthropicClaudeMessagesConfig,
     AmazonAnthropicClaudeMessagesStreamDecoder,
@@ -178,3 +179,99 @@ def test_remove_ttl_from_cache_control():
     request5 = {}
     cfg._remove_ttl_from_cache_control(request5)
     assert request5 == {}
+
+
+def test_remove_custom_field_from_tools():
+    """
+    Ensure the `custom` field is stripped from every tool definition.
+
+    Claude Code v2.1.69+ sends `custom: {defer_loading: true}` on tool
+    objects.  Bedrock does not accept this extra field and returns
+    "Extra inputs are not permitted".
+
+    Ref: https://github.com/BerriAI/litellm/issues/22847
+    """
+
+    # Case 1: tool with `custom` field should have it removed
+    request = {
+        "tools": [
+            {
+                "name": "Read",
+                "description": "Read a file",
+                "input_schema": {"type": "object", "properties": {}},
+                "custom": {"defer_loading": True},
+            },
+            {
+                "name": "Write",
+                "description": "Write a file",
+                "input_schema": {"type": "object", "properties": {}},
+            },
+        ]
+    }
+
+    remove_custom_field_from_tools(request)
+
+    for tool in request["tools"]:
+        assert "custom" not in tool, f"Tool {tool['name']} still has 'custom' field"
+    # Other fields should be preserved
+    assert request["tools"][0]["name"] == "Read"
+    assert request["tools"][1]["name"] == "Write"
+
+    # Case 2: request without tools key (should not raise error)
+    request2 = {"messages": [{"role": "user", "content": "hi"}]}
+    remove_custom_field_from_tools(request2)
+    assert "tools" not in request2
+
+    # Case 3: empty tools list (should not raise error)
+    request3 = {"tools": []}
+    remove_custom_field_from_tools(request3)
+    assert request3["tools"] == []
+
+    # Case 4: tools with None value (should not raise error)
+    request4 = {"tools": None}
+    remove_custom_field_from_tools(request4)
+    assert request4["tools"] is None
+
+def test_remove_scope_from_cache_control():
+    """Ensure scope field is removed from cache_control for Bedrock (not supported)."""
+
+    cfg = AmazonAnthropicClaudeMessagesConfig()
+
+    # Test case 1: System with cache_control containing scope
+    request = {
+        "system": [
+            {
+                "type": "text",
+                "text": "You are an AI assistant.",
+                "cache_control": {
+                    "type": "ephemeral",
+                    "scope": "global",
+                },
+            }
+        ],
+        "messages": [
+            {
+                "role": "user",
+                "content": [
+                    {
+                        "type": "text",
+                        "text": "Hello",
+                        "cache_control": {
+                            "type": "ephemeral",
+                            "scope": "global",
+                        },
+                    }
+                ],
+            }
+        ],
+    }
+
+    cfg._remove_ttl_from_cache_control(request)
+
+    # Verify scope is removed from system
+    assert "scope" not in request["system"][0]["cache_control"]
+    assert request["system"][0]["cache_control"]["type"] == "ephemeral"
+
+    # Verify scope is removed from messages
+    assert "scope" not in request["messages"][0]["content"][0]["cache_control"]
+    assert request["messages"][0]["content"][0]["cache_control"]["type"] == "ephemeral"