fix(schema): reject context param not immediately after self/cls

The self_or_cls_skipped flag persisted across all remaining params,
so `def f(self, x: int, ctx: RunContextWrapper)` incorrectly passed
validation. Now only the param at index 1 (immediately after self/cls)
is treated as the effective first param.

Adds a test for this edge case.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mvanhorn

src/agents/function_schema.py

@@ -306,14 +306,15 @@ def function_schema(
             filtered_params.append((first_name, first_param))
 
     # For parameters other than the first, raise error if any use RunContextWrapper or ToolContext
-    # (unless self/cls was skipped, in which case the second param is the effective first param).
-    for name, param in params[1:]:
+    # (unless self/cls was skipped, in which case ONLY the param immediately after self/cls is
+    # treated as the effective first param).
+    for idx, (name, param) in enumerate(params[1:]):
         ann = type_hints.get(name, param.annotation)
         if ann != inspect._empty:
             origin = get_origin(ann) or ann
             if origin is RunContextWrapper or origin is ToolContext:
-                if self_or_cls_skipped and not takes_context:
-                    # self/cls was the first param, so this is the effective first param
+                if self_or_cls_skipped and not takes_context and idx == 0:
+                    # self/cls was the first param and this is immediately after it
                     takes_context = True
                     self_or_cls_skipped = False
                     continue

tests/test_function_schema.py

@@ -934,6 +934,18 @@ def greet(self, ctx: RunContextWrapper[None], name: str) -> str:
     assert fs.takes_context is True
 
 
+def test_method_context_not_immediately_after_self_raises():
+    """Test that RunContextWrapper at position 3+ (not immediately after self) raises UserError."""
+
+    class MyTools:
+        def greet(self, name: str, ctx: RunContextWrapper[None]) -> str:
+            return f"Hello, {name}"
+
+    obj = MyTools()
+    with pytest.raises(UserError, match="non-first position"):
+        function_schema(obj.greet, use_docstring_info=False)
+
+
 def test_regular_unannotated_first_param_still_included():
     """Test that a regular unannotated first param (not self/cls) is still included."""