feat: Updated schema additional properties to false when strict tool use

Author: BV-Venky

src/strands/models/anthropic.py

@@ -20,6 +20,7 @@
 from ..types.exceptions import ContextWindowOverflowException, ModelThrottledException
 from ..types.streaming import StreamEvent
 from ..types.tools import ToolChoice, ToolChoiceToolDict, ToolSpec
+from ._strict_schema import ensure_strict_json_schema
 from ._validation import _has_location_source, validate_config_keys
 from .model import BaseModelConfig, Model
 
@@ -231,7 +232,11 @@ def format_request(
                 {
                     "name": tool_spec["name"],
                     "description": tool_spec["description"],
-                    "input_schema": tool_spec["inputSchema"]["json"],
+                    "input_schema": (
+                        ensure_strict_json_schema(tool_spec["inputSchema"]["json"])
+                        if tool_spec.get("strict")
+                        else tool_spec["inputSchema"]["json"]
+                    ),
                     **({"strict": tool_spec["strict"]} if "strict" in tool_spec else {}),
                 }
                 for tool_spec in tool_specs or []

src/strands/models/openai.py

@@ -21,6 +21,7 @@
 from ..types.exceptions import ContextWindowOverflowException, ModelThrottledException
 from ..types.streaming import StreamEvent
 from ..types.tools import ToolChoice, ToolResult, ToolSpec, ToolUse
+from ._strict_schema import ensure_strict_json_schema
 from ._validation import _has_location_source, validate_config_keys
 from .model import BaseModelConfig, Model
 
@@ -481,7 +482,11 @@ def format_request(
                     "function": {
                         "name": tool_spec["name"],
                         "description": tool_spec["description"],
-                        "parameters": tool_spec["inputSchema"]["json"],
+                        "parameters": (
+                            ensure_strict_json_schema(tool_spec["inputSchema"]["json"], require_all_properties=True)
+                            if tool_spec.get("strict")
+                            else tool_spec["inputSchema"]["json"]
+                        ),
                         **({"strict": tool_spec["strict"]} if "strict" in tool_spec else {}),
                     },
                 }

src/strands/models/openai_responses.py

@@ -58,6 +58,7 @@
 from ..types.exceptions import ContextWindowOverflowException, ModelThrottledException  # noqa: E402
 from ..types.streaming import StreamEvent  # noqa: E402
 from ..types.tools import ToolChoice, ToolResult, ToolSpec, ToolUse  # noqa: E402
+from ._strict_schema import ensure_strict_json_schema  # noqa: E402
 from ._validation import validate_config_keys  # noqa: E402
 from .model import BaseModelConfig, Model  # noqa: E402
 
@@ -516,7 +517,11 @@ def _format_request(
                     "type": "function",
                     "name": tool_spec["name"],
                     "description": tool_spec.get("description", ""),
-                    "parameters": tool_spec["inputSchema"]["json"],
+                    "parameters": (
+                        ensure_strict_json_schema(tool_spec["inputSchema"]["json"], require_all_properties=True)
+                        if tool_spec.get("strict")
+                        else tool_spec["inputSchema"]["json"]
+                    ),
                     **({"strict": tool_spec["strict"]} if "strict" in tool_spec else {}),
                 }
                 for tool_spec in tool_specs

tests/strands/models/test_anthropic.py

@@ -460,12 +460,22 @@ def test_format_request_tool_choice_auto(model, messages, model_id, max_tokens):
 
 
 def test_format_request_tool_specs_with_strict(model, messages, model_id, max_tokens):
-    tool_specs = [
-        {"description": "test tool", "name": "test_tool", "inputSchema": {"json": {"key": "value"}}, "strict": True}
-    ]
-    tru_request = model.format_request(messages, tool_specs)
+    strict_tool_spec = {
+        "description": "description",
+        "name": "name",
+        "inputSchema": {
+            "json": {
+                "type": "object",
+                "properties": {"x": {"type": "string"}},
+            }
+        },
+        "strict": True,
+    }
+    tru_request = model.format_request(messages, tool_specs=[strict_tool_spec])
+    tool_in_request = tru_request["tools"][0]
 
-    assert tru_request["tools"][0]["strict"] is True
+    assert tool_in_request["strict"] is True
+    assert tool_in_request["input_schema"]["additionalProperties"] is False
 
 
 def test_format_request_tool_specs_with_strict_false(model, messages, model_id, max_tokens):

tests/strands/models/test_openai.py

@@ -642,14 +642,21 @@ def test_format_request_tool_specs_with_strict(model, messages, system_prompt):
             "name": "test_tool",
             "description": "A test tool",
             "inputSchema": {
-                "json": {"type": "object", "properties": {"input": {"type": "string"}}, "required": ["input"]}
+                "json": {
+                    "type": "object",
+                    "properties": {"input": {"type": "string"}, "optional_input": {"type": "string"}},
+                    "required": ["input"],
+                }
             },
             "strict": True,
         }
     ]
     tru_request = model.format_request(messages, strict_tool_specs, system_prompt)
 
-    assert tru_request["tools"][0]["function"]["strict"] is True
+    tool_function = tru_request["tools"][0]["function"]
+    assert tool_function["strict"] is True
+    assert tool_function["parameters"]["additionalProperties"] is False
+    assert set(tool_function["parameters"]["required"]) == {"input", "optional_input"}
 
 
 def test_format_request_tool_specs_with_strict_false(model, messages, system_prompt):

tests/strands/models/test_openai_responses.py

@@ -355,14 +355,21 @@ def test_format_request_tool_specs_with_strict(model, messages, system_prompt):
             "name": "test_tool",
             "description": "A test tool",
             "inputSchema": {
-                "json": {"type": "object", "properties": {"input": {"type": "string"}}, "required": ["input"]}
+                "json": {
+                    "type": "object",
+                    "properties": {"input": {"type": "string"}, "optional_input": {"type": "string"}},
+                    "required": ["input"],
+                }
             },
             "strict": True,
         }
     ]
     tru_request = model._format_request(messages, strict_tool_specs, system_prompt)
 
-    assert tru_request["tools"][0]["strict"] is True
+    tool = tru_request["tools"][0]
+    assert tool["strict"] is True
+    assert tool["parameters"]["additionalProperties"] is False
+    assert set(tool["parameters"]["required"]) == {"input", "optional_input"}
 
 
 def test_format_request_tool_specs_with_strict_false(model, messages, system_prompt):

tests_integ/models/test_model_anthropic.py

@@ -221,3 +221,17 @@ async def test_count_tokens_with_tools_greater_than_without(self, model, message
         without = await model.count_tokens(messages=messages)
         with_tools = await model.count_tokens(messages=messages, tool_specs=tool_specs, system_prompt="Be helpful.")
         assert with_tools > without
+
+
+def test_strict_tool_integration(model):
+    """Test that a strict tool invocation is accepted by the Anthropic API without a 400 validation error."""
+
+    @strands.tool(strict=True)
+    def strict_tool(text: str) -> str:
+        """A strict tool for testing."""
+        return f"Echo: {text}"
+
+    agent = Agent(model=model, tools=[strict_tool])
+    # The API should accept the request and respond normally without throwing a 400 validation error
+    result = agent("Call the strict tool with the text 'hello'")
+    assert result.message is not None

tests_integ/models/test_model_openai.py

@@ -438,3 +438,17 @@ async def test_count_tokens_with_tools_greater_than_without(self, model, message
         without = await model.count_tokens(messages=messages)
         with_tools = await model.count_tokens(messages=messages, tool_specs=tool_specs, system_prompt="Be helpful.")
         assert with_tools > without
+
+
+def test_strict_tool_integration(model):
+    """Test that a strict tool invocation is accepted by the OpenAI API without a 400 validation error."""
+
+    @strands.tool(strict=True)
+    def strict_tool(text: str) -> str:
+        """A strict tool for testing."""
+        return f"Echo: {text}"
+
+    agent = Agent(model=model, tools=[strict_tool])
+    # The API should accept the request and respond normally without throwing a 400 validation error
+    result = agent("Call the strict tool with the text 'hello'")
+    assert result.message is not None