fix(bedrock): strip custom tool fields for Converse API to fix Haiku 4.5 rejection

Claude Code sends custom: {eager_input_streaming: true} on tool definitions.
Bedrock Converse accepts this for Claude 4 models (Sonnet 4.6, Opus 4.6) but
rejects it for Haiku 4.5 with 'Extra inputs are not permitted'.

- Add strip_custom_from_tools_list() in common_utils for list-based stripping
- Refactor remove_custom_field_from_tools to use the new helper
- Call strip_custom_from_tools_list in _process_tools_and_beta before
  passing tools to _bedrock_tools_pt
- Add unit tests for strip_custom_from_tools_list and _process_tools_and_beta

Fixes #23825
Related: #16679

Made-with: Cursor

litellm/llms/bedrock/chat/converse_transformation.py

@@ -73,6 +73,7 @@ from ..common_utils import (
     get_anthropic_beta_from_headers,
     get_bedrock_tool_name,
     is_claude_4_5_on_bedrock,
+    strip_custom_from_tools_list,
 )
 
 # Computer use tool prefixes supported by Bedrock
@@ -1299,6 +1300,12 @@ class AmazonConverseConfig(BaseConfig):
                     continue
                 filtered_tools.append(tool)
 
+        # Strip custom field from tools before sending to Bedrock Converse.
+        # Claude Code sends custom: {eager_input_streaming: true} etc. which Anthropic
+        # accepts but Bedrock rejects for some models (e.g. Haiku 4.5) with
+        # "Extra inputs are not permitted". Ref: https://github.com/BerriAI/litellm/issues/23825
+        strip_custom_from_tools_list(filtered_tools)
+
         # Only separate tools if computer use tools are actually present
         if filtered_tools and self.is_computer_use_tool_used(filtered_tools, model):
             # Separate computer use tools from regular function tools

litellm/llms/bedrock/common_utils.py

@@ -63,11 +63,36 @@ def remove_custom_field_from_tools(request_body: dict) -> None:
     Ref: https://github.com/BerriAI/litellm/issues/22847
     """
     tools = request_body.get("tools")
+    if not tools or not isinstance(tools, list):
+        return
+    strip_custom_from_tools_list(tools)
+
+
+def strip_custom_from_tools_list(tools: list) -> None:
+    """
+    Strip ``custom`` field from each tool in the list (modifies in-place).
+
+    Claude Code sends Anthropic-specific fields like ``custom: {eager_input_streaming: true}``
+    or ``custom: {input_examples: [...]}`` on tool definitions. Anthropic's API accepts these
+    but Bedrock Converse rejects them with "Extra inputs are not permitted" for some models
+    (e.g. Haiku 4.5).
+
+    Handles both top-level tool ``custom`` and nested ``function.custom`` (OpenAI format).
+
+    Args:
+        tools: List of tool dicts to modify in-place.
+
+    Ref: https://github.com/BerriAI/litellm/issues/23825
+    Ref: https://github.com/BerriAI/litellm/issues/16679
+    """
     if not tools or not isinstance(tools, list):
         return
     for tool in tools:
         if isinstance(tool, dict):
             tool.pop("custom", None)
+            func = tool.get("function")
+            if isinstance(func, dict):
+                func.pop("custom", None)
 
 
 class AmazonBedrockGlobalConfig:

tests/test_litellm/llms/bedrock/chat/test_converse_transformation.py

@@ -319,6 +319,45 @@ def test_get_supported_openai_params_bedrock_converse():
         print(f"✅ Passed for model: {model}")
 
 
+def test_process_tools_and_beta_strips_custom_field():
+    """
+    Test that _process_tools_and_beta strips custom field from tools before sending to Bedrock.
+
+    Claude Code sends custom: {eager_input_streaming: true} on tool definitions.
+    Bedrock Converse rejects this for Haiku 4.5 with "Extra inputs are not permitted".
+    Ref: https://github.com/BerriAI/litellm/issues/23825
+    """
+    config = AmazonConverseConfig()
+    tools_with_custom = [
+        {
+            "type": "function",
+            "function": {
+                "name": "get_weather",
+                "description": "Get the weather",
+                "parameters": {
+                    "type": "object",
+                    "properties": {"location": {"type": "string"}},
+                    "required": ["location"],
+                },
+            },
+            "custom": {"eager_input_streaming": True},
+        },
+    ]
+    additional_params = {}
+    bedrock_tools, _ = config._process_tools_and_beta(
+        original_tools=tools_with_custom,
+        model="us.anthropic.claude-haiku-4-5-20251001-v1:0",
+        headers=None,
+        additional_request_params=additional_params,
+    )
+    # Should produce valid Bedrock tools (toolSpec format) without custom
+    assert len(bedrock_tools) == 1
+    assert "toolSpec" in bedrock_tools[0]
+    assert bedrock_tools[0]["toolSpec"]["name"] == "get_weather"
+    # Original tools list should have been modified in-place (custom stripped)
+    assert "custom" not in tools_with_custom[0]
+
+
 def test_transform_request_helper_includes_anthropic_beta_and_tools():
     """Test _transform_request_helper includes anthropic_beta for computer tools."""
     config = AmazonConverseConfig()

tests/test_litellm/llms/bedrock/test_bedrock_common_utils.py

@@ -10,7 +10,84 @@ sys.path.insert(
 )  # Adds the parent directory to the system path
 
 
-from litellm.llms.bedrock.common_utils import BedrockModelInfo
+from litellm.llms.bedrock.common_utils import (
+    BedrockModelInfo,
+    remove_custom_field_from_tools,
+    strip_custom_from_tools_list,
+)
+
+
+def test_strip_custom_from_tools_list():
+    """
+    Ensure strip_custom_from_tools_list removes custom field from tools.
+
+    Claude Code sends custom: {eager_input_streaming: true} or custom: {input_examples: [...]}
+    on tool definitions. Bedrock Converse rejects these for some models (e.g. Haiku 4.5)
+    with "Extra inputs are not permitted".
+
+    Ref: https://github.com/BerriAI/litellm/issues/23825
+    Ref: https://github.com/BerriAI/litellm/issues/16679
+    """
+    # Case 1: OpenAI format - custom at tool level
+    tools = [
+        {
+            "type": "function",
+            "function": {
+                "name": "get_weather",
+                "description": "Get weather",
+                "parameters": {"type": "object", "properties": {}},
+            },
+            "custom": {"eager_input_streaming": True},
+        },
+    ]
+    strip_custom_from_tools_list(tools)
+    assert "custom" not in tools[0]
+    assert tools[0]["function"]["name"] == "get_weather"
+
+    # Case 2: OpenAI format - custom nested in function
+    tools2 = [
+        {
+            "type": "function",
+            "function": {
+                "name": "search",
+                "parameters": {},
+                "custom": {"input_examples": [{"query": "test"}]},
+            },
+        },
+    ]
+    strip_custom_from_tools_list(tools2)
+    assert "custom" not in tools2[0]["function"]
+
+    # Case 3: Anthropic format - custom at top level
+    tools3 = [
+        {
+            "name": "some_tool",
+            "input_schema": {"type": "object"},
+            "custom": {"eager_input_streaming": True},
+        },
+    ]
+    strip_custom_from_tools_list(tools3)
+    assert "custom" not in tools3[0]
+    assert tools3[0]["name"] == "some_tool"
+
+    # Case 4: empty list (no-op)
+    tools4 = []
+    strip_custom_from_tools_list(tools4)
+    assert tools4 == []
+
+    # Case 5: None (no-op)
+    strip_custom_from_tools_list(None)  # type: ignore
+
+
+def test_remove_custom_field_from_tools_uses_strip_custom_from_tools_list():
+    """Ensure remove_custom_field_from_tools delegates to strip_custom_from_tools_list."""
+    request = {
+        "tools": [
+            {"name": "tool1", "input_schema": {}, "custom": {"eager_input_streaming": True}},
+        ]
+    }
+    remove_custom_field_from_tools(request)
+    assert "custom" not in request["tools"][0]
 
 
 def test_deepseek_cris():