feat(bedrock): forward strict and additionalProperties to Converse toolSpec (#29814)

* feat(bedrock): forward strict and additionalProperties to Converse toolSpec

Bedrock Converse supports strict in toolSpec since 2026-02, but
_bedrock_tools_pt only whitelisted type/properties/required/name/description,
so strict: true was silently dropped and Claude-on-Bedrock ignored enum
constraints that GPT and direct-Anthropic honored. Forward strict from the
OpenAI function and additionalProperties from the schema (Bedrock requires
the latter alongside strict), passing each only when present.

https://claude.ai/code/session_01WQjWd8NfUB3vxERwudbHkv

* fix(bedrock): only forward strict tool schemas to Claude on Converse

Nova, Llama and GPT-OSS on Bedrock reject the strict field
(BedrockException 'This model doesn't support the strict field'), and the
GPT-OSS request-body test asserts strict/additionalProperties are stripped.
Forwarding them to every model broke the llm_translation suite, so gate the
forwarding on the anthropic base model since only Claude honours strict
tool schemas on Bedrock.

litellm/litellm_core_utils/prompt_templates/factory.py

@@ -5496,6 +5496,7 @@ def _bedrock_tools_pt(
     ]
     """
     from litellm.llms.bedrock.common_utils import (
+        get_bedrock_base_model,
         normalize_json_schema_custom_types_to_object,
     )
     from litellm.litellm_core_utils.prompt_templates.common_utils import unpack_defs
@@ -5503,6 +5504,11 @@ def _bedrock_tools_pt(
     _valid_json_schema_root_types = frozenset(
         ("array", "boolean", "integer", "null", "number", "object", "string")
     )
+    # Only Claude on Bedrock honours strict tool schemas; other families
+    # (Nova, Llama, GPT-OSS) reject the strict field outright.
+    supports_strict_tools = bool(
+        model and get_bedrock_base_model(model).startswith("anthropic")
+    )
     tool_block_list: List[BedrockToolBlock] = []
     for tool_idx, tool in enumerate(tools):
         # Check if tool is already a BedrockToolBlock (e.g., systemTool for Nova grounding)
@@ -5548,16 +5554,21 @@ def _bedrock_tools_pt(
         normalize_json_schema_custom_types_to_object(parameters)
         if parameters.get("type") not in _valid_json_schema_root_types:
             parameters["type"] = "object"
-        tool_input_schema = BedrockToolInputSchemaBlock(
+        json_schema = BedrockToolJsonSchemaBlock(
-            json=BedrockToolJsonSchemaBlock(
+            type=parameters["type"],
-                type=parameters["type"],
+            properties=parameters.get("properties", {}),
-                properties=parameters.get("properties", {}),
+            required=parameters.get("required", []),
-                required=parameters.get("required", []),
-            )
         )
+        additional_properties = parameters.get("additionalProperties", None)
+        if supports_strict_tools and additional_properties is not None:
+            json_schema["additionalProperties"] = additional_properties
+        tool_input_schema = BedrockToolInputSchemaBlock(json=json_schema)
         tool_spec = BedrockToolSpecBlock(
             inputSchema=tool_input_schema, name=name, description=description
         )
+        strict = tool.get("function", {}).get("strict", None)
+        if supports_strict_tools and strict is not None:
+            tool_spec["strict"] = strict
         tool_block = BedrockToolBlock(toolSpec=tool_spec)
         tool_block_list.append(tool_block)
 

litellm/types/llms/bedrock.py

@@ -250,6 +250,7 @@ class ToolJsonSchemaBlock(TypedDict, total=False):
     type: Literal["object"]
     properties: dict
     required: List[str]
+    additionalProperties: bool
 
 
 class ToolInputSchemaBlock(TypedDict):
@@ -260,6 +261,7 @@ class ToolSpecBlock(TypedDict, total=False):
     inputSchema: Required[ToolInputSchemaBlock]
     name: Required[str]
     description: str
+    strict: bool
 
 
 class SystemToolBlock(TypedDict, total=False):

tests/test_litellm/litellm_core_utils/prompt_templates/test_litellm_core_utils_prompt_templates_factory.py

@@ -898,6 +898,61 @@ def test_bedrock_tools_unpack_defs():
     _bedrock_tools_pt(tools=tools)
 
 
+def test_bedrock_tools_pt_strict_parameter():
+    """Regression for strict tools on the Bedrock Converse path.
+
+    Claude on Bedrock honours strict in toolSpec (with additionalProperties, which
+    Bedrock requires alongside strict); without forwarding it the model ignores the
+    enum constraint the caller asked for. Every other Bedrock family (Nova, Llama,
+    GPT-OSS) rejects the strict field, so it must only be forwarded for Claude.
+    """
+    tools_with_strict = [
+        {
+            "type": "function",
+            "function": {
+                "name": "generate_sql",
+                "strict": True,
+                "description": "Generate a SQL query",
+                "parameters": {
+                    "type": "object",
+                    "properties": {"query": {"type": "string"}},
+                    "required": ["query"],
+                    "additionalProperties": False,
+                },
+            },
+        }
+    ]
+    result = _bedrock_tools_pt(
+        tools_with_strict, model="anthropic.claude-sonnet-4-5-20250929-v1:0"
+    )
+    assert result[0]["toolSpec"]["strict"] is True
+    assert result[0]["toolSpec"]["inputSchema"]["json"]["additionalProperties"] is False
+
+    result = _bedrock_tools_pt(tools_with_strict, model="us.amazon.nova-micro-v1:0")
+    assert "strict" not in result[0]["toolSpec"]
+    assert "additionalProperties" not in result[0]["toolSpec"]["inputSchema"]["json"]
+
+    tools_without_strict = [
+        {
+            "type": "function",
+            "function": {
+                "name": "generate_sql",
+                "description": "Generate a SQL query",
+                "parameters": {
+                    "type": "object",
+                    "properties": {"query": {"type": "string"}},
+                    "required": ["query"],
+                },
+            },
+        }
+    ]
+    result = _bedrock_tools_pt(
+        tools_without_strict, model="anthropic.claude-sonnet-4-5-20250929-v1:0"
+    )
+    assert "strict" not in result[0]["toolSpec"]
+    assert "additionalProperties" not in result[0]["toolSpec"]["inputSchema"]["json"]
+
+
 def test_bedrock_image_processor_content_type_fallback_url_extension():
     """
     Test that _post_call_image_processing falls back to URL extension