enhancement: Add tool_name to ToolContext to support shared tool handlers (#1043)

This adds a `tool_name` field to `ToolContext`, which gets passed into
the `on_invoke_tool` handler. Helpful for scenarios where we dynamically
register multiple tools that all share a single generic handler e.g.in
multi-agent setups.

As such, by including the name of the tool that was invoked, the handler
can now easily branch logic or route requests accordingly.

Resolves  #1030 

All tests pass. and here is a script to test it out
https://gist.github.com/vrtnis/ca354244f7a5ecd9a73c0a2d34cb194b

---------

Co-authored-by: Kazuhiro Sera <seratch@openai.com>

Author: vrtnis

docs/ref/tool_context.md

@@ -0,0 +1,3 @@
+# `Tool context`
+
+::: agents.tool_context

docs/tools.md

@@ -180,7 +180,7 @@ Sometimes, you don't want to use a Python function as a tool. You can directly c
 -   `name`
 -   `description`
 -   `params_json_schema`, which is the JSON schema for the arguments
--   `on_invoke_tool`, which is an async function that receives the context and the arguments as a JSON string, and must return the tool output as a string.
+-   `on_invoke_tool`, which is an async function that receives a [`ToolContext`][agents.tool_context.ToolContext] and the arguments as a JSON string, and must return the tool output as a string.
 
 ```python
 from typing import Any

mkdocs.yml

@@ -92,6 +92,7 @@ plugins:
                     - ref/lifecycle.md
                     - ref/items.md
                     - ref/run_context.md
+                    - ref/tool_context.md
                     - ref/usage.md
                     - ref/exceptions.md
                     - ref/guardrail.md

src/agents/_run_impl.py

@@ -548,7 +548,11 @@ async def run_single_tool(
             func_tool: FunctionTool, tool_call: ResponseFunctionToolCall
         ) -> Any:
             with function_span(func_tool.name) as span_fn:
-                tool_context = ToolContext.from_agent_context(context_wrapper, tool_call.call_id)
+                tool_context = ToolContext.from_agent_context(
+                    context_wrapper,
+                    tool_call.call_id,
+                    tool_call=tool_call,
+                )
                 if config.trace_include_sensitive_data:
                     span_fn.span_data.input = tool_call.arguments
                 try:

src/agents/tool_context.py

@@ -1,5 +1,7 @@
 from dataclasses import dataclass, field, fields
-from typing import Any
+from typing import Any, Optional
+
+from openai.types.responses import ResponseFunctionToolCall
 
 from .run_context import RunContextWrapper, TContext
 
@@ -8,16 +10,26 @@ def _assert_must_pass_tool_call_id() -> str:
     raise ValueError("tool_call_id must be passed to ToolContext")
 
 
+def _assert_must_pass_tool_name() -> str:
+    raise ValueError("tool_name must be passed to ToolContext")
+
+
 @dataclass
 class ToolContext(RunContextWrapper[TContext]):
     """The context of a tool call."""
 
+    tool_name: str = field(default_factory=_assert_must_pass_tool_name)
+    """The name of the tool being invoked."""
+
     tool_call_id: str = field(default_factory=_assert_must_pass_tool_call_id)
     """The ID of the tool call."""
 
     @classmethod
     def from_agent_context(
-        cls, context: RunContextWrapper[TContext], tool_call_id: str
+        cls,
+        context: RunContextWrapper[TContext],
+        tool_call_id: str,
+        tool_call: Optional[ResponseFunctionToolCall] = None,
     ) -> "ToolContext":
         """
         Create a ToolContext from a RunContextWrapper.
@@ -26,4 +38,5 @@ def from_agent_context(
         base_values: dict[str, Any] = {
             f.name: getattr(context, f.name) for f in fields(RunContextWrapper) if f.init
         }
-        return cls(tool_call_id=tool_call_id, **base_values)
+        tool_name = tool_call.name if tool_call is not None else _assert_must_pass_tool_name()
+        return cls(tool_name=tool_name, tool_call_id=tool_call_id, **base_values)

tests/test_function_tool.py

@@ -26,7 +26,9 @@ async def test_argless_function():
     tool = function_tool(argless_function)
     assert tool.name == "argless_function"
 
-    result = await tool.on_invoke_tool(ToolContext(context=None, tool_call_id="1"), "")
+    result = await tool.on_invoke_tool(
+        ToolContext(context=None, tool_name=tool.name, tool_call_id="1"), ""
+    )
     assert result == "ok"
 
 
@@ -39,11 +41,13 @@ async def test_argless_with_context():
     tool = function_tool(argless_with_context)
     assert tool.name == "argless_with_context"
 
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), "")
+    result = await tool.on_invoke_tool(ToolContext(None, tool_name=tool.name, tool_call_id="1"), "")
     assert result == "ok"
 
     # Extra JSON should not raise an error
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), '{"a": 1}')
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), '{"a": 1}'
+    )
     assert result == "ok"
 
 
@@ -56,15 +60,19 @@ async def test_simple_function():
     tool = function_tool(simple_function, failure_error_function=None)
     assert tool.name == "simple_function"
 
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), '{"a": 1}')
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), '{"a": 1}'
+    )
     assert result == 6
 
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), '{"a": 1, "b": 2}')
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), '{"a": 1, "b": 2}'
+    )
     assert result == 3
 
     # Missing required argument should raise an error
     with pytest.raises(ModelBehaviorError):
-        await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), "")
+        await tool.on_invoke_tool(ToolContext(None, tool_name=tool.name, tool_call_id="1"), "")
 
 
 class Foo(BaseModel):
@@ -92,7 +100,9 @@ async def test_complex_args_function():
             "bar": Bar(x="hello", y=10),
         }
     )
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), valid_json)
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), valid_json
+    )
     assert result == "6 hello10 hello"
 
     valid_json = json.dumps(
@@ -101,7 +111,9 @@ async def test_complex_args_function():
             "bar": Bar(x="hello", y=10),
         }
     )
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), valid_json)
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), valid_json
+    )
     assert result == "3 hello10 hello"
 
     valid_json = json.dumps(
@@ -111,12 +123,16 @@ async def test_complex_args_function():
             "baz": "world",
         }
     )
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), valid_json)
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), valid_json
+    )
     assert result == "3 hello10 world"
 
     # Missing required argument should raise an error
     with pytest.raises(ModelBehaviorError):
-        await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), '{"foo": {"a": 1}}')
+        await tool.on_invoke_tool(
+            ToolContext(None, tool_name=tool.name, tool_call_id="1"), '{"foo": {"a": 1}}'
+        )
 
 
 def test_function_config_overrides():
@@ -176,7 +192,9 @@ async def run_function(ctx: RunContextWrapper[Any], args: str) -> str:
         assert tool.params_json_schema[key] == value
     assert tool.strict_json_schema
 
-    result = await tool.on_invoke_tool(ToolContext(None, tool_call_id="1"), '{"data": "hello"}')
+    result = await tool.on_invoke_tool(
+        ToolContext(None, tool_name=tool.name, tool_call_id="1"), '{"data": "hello"}'
+    )
     assert result == "hello_done"
 
     tool_not_strict = FunctionTool(
@@ -191,7 +209,8 @@ async def run_function(ctx: RunContextWrapper[Any], args: str) -> str:
     assert "additionalProperties" not in tool_not_strict.params_json_schema
 
     result = await tool_not_strict.on_invoke_tool(
-        ToolContext(None, tool_call_id="1"), '{"data": "hello", "bar": "baz"}'
+        ToolContext(None, tool_name=tool_not_strict.name, tool_call_id="1"),
+        '{"data": "hello", "bar": "baz"}',
     )
     assert result == "hello_done"
 
@@ -202,7 +221,7 @@ def my_func(a: int, b: int = 5):
         raise ValueError("test")
 
     tool = function_tool(my_func)
-    ctx = ToolContext(None, tool_call_id="1")
+    ctx = ToolContext(None, tool_name=tool.name, tool_call_id="1")
 
     result = await tool.on_invoke_tool(ctx, "")
     assert "Invalid JSON" in str(result)
@@ -226,7 +245,7 @@ def custom_sync_error_function(ctx: RunContextWrapper[Any], error: Exception) ->
         return f"error_{error.__class__.__name__}"
 
     tool = function_tool(my_func, failure_error_function=custom_sync_error_function)
-    ctx = ToolContext(None, tool_call_id="1")
+    ctx = ToolContext(None, tool_name=tool.name, tool_call_id="1")
 
     result = await tool.on_invoke_tool(ctx, "")
     assert result == "error_ModelBehaviorError"
@@ -250,7 +269,7 @@ def custom_sync_error_function(ctx: RunContextWrapper[Any], error: Exception) ->
         return f"error_{error.__class__.__name__}"
 
     tool = function_tool(my_func, failure_error_function=custom_sync_error_function)
-    ctx = ToolContext(None, tool_call_id="1")
+    ctx = ToolContext(None, tool_name=tool.name, tool_call_id="1")
 
     result = await tool.on_invoke_tool(ctx, "")
     assert result == "error_ModelBehaviorError"

tests/test_function_tool_decorator.py

@@ -16,7 +16,7 @@ def __init__(self):
 
 
 def ctx_wrapper() -> ToolContext[DummyContext]:
-    return ToolContext(context=DummyContext(), tool_call_id="1")
+    return ToolContext(context=DummyContext(), tool_name="dummy", tool_call_id="1")
 
 
 @function_tool