fix: make ToolContext hashable to match RunContextWrapper

ToolContext was decorated with bare @DataClass, which sets
__hash__ = None when eq defaults to True. Its parent
RunContextWrapper uses @DataClass(eq=False) and is hashable by
identity, so the subclass silently dropped the parent's
hashability contract. Switch ToolContext to @DataClass(eq=False)
to restore consistency with the parent and add a regression test.

Author: ioleksiuk

src/agents/tool_context.py

@@ -32,7 +32,7 @@ def _assert_must_pass_tool_arguments() -> str:
 _MISSING = object()
 
 
-@dataclass
+@dataclass(eq=False)
 class ToolContext(RunContextWrapper[TContext]):
     """The context of a tool call."""
 

tests/test_tool_context.py

@@ -12,6 +12,23 @@
 from tests.utils.hitl import make_context_wrapper
 
 
+def test_tool_context_is_hashable_like_run_context_wrapper() -> None:
+    # RunContextWrapper is declared with @dataclass(eq=False) so instances remain
+    # hashable by identity. ToolContext inherits from it and must preserve that
+    # contract; a bare @dataclass on the subclass would set __hash__ = None.
+    parent: RunContextWrapper[dict[str, object]] = RunContextWrapper(context={})
+    child: ToolContext[dict[str, object]] = ToolContext(
+        context={},
+        tool_name="t",
+        tool_call_id="call-hash",
+        tool_arguments="{}",
+    )
+
+    assert hash(parent) == hash(parent)
+    assert hash(child) == hash(child)
+    assert {child: "value"}[child] == "value"
+
+
 def test_tool_context_requires_fields() -> None:
     ctx: RunContextWrapper[dict[str, object]] = RunContextWrapper(context={})
     with pytest.raises(ValueError):