[BUG] Direct tool calls for tools w/ `context=True` cause KeyError

[q-maze]

Checks

• I have updated to the lastest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched ./issues and there are no duplicates of my issue

Strands Version

1.17.0

Python Version

3.13.4

Operating System

macOS 15.7

Installation Method

pip

Steps to Reproduce

from strands import Agent, ToolContext, tool

@tool(context=True)
def add_w_state(a: int, b:int, tool_context: ToolContext) -> int:
    result = a + b
    tool_context.agent.state.set("last_add_result", result)
    return result


def main():
    agent = Agent(tools=[add_w_state])
    agent.tool.add_w_state(a=1, b=1)
    print(agent.messages)


if __name__ == "__main__":
    main()

Expected Behavior

Direct method calls for tools with context should not cause an error.

[{'content': [{'text': 'agent.tool. add_w_state direct tool call.\n'
                       'Input parameters: {"a": 1, "b": 1}\n'}],
  'role': 'user'},
 {'content': [{'toolUse': {'input': {'a': 1, 'b': 1},
                           'name': 'add_w_state',
                           'toolUseId': 'tooluse_add_w_state_975207425'}}],
  'role': 'assistant'},
 {'content': [{'toolResult': {'content': [{'text': '2'}],
                              'status': 'success',
                              'toolUseId': 'tooluse_add_w_state_975207425'}}],
  'role': 'user'},
 {'content': [{'text': 'agent.tool. add_w_state was called.'}], 'role': 'assistant'}]

Actual Behavior

Direct method calls for tools with context causes an error.

[{'content': [{'text': 'agent.tool.add_w_state direct tool call.\n'
                       'Input parameters: {"a": 1, "b": 1}\n'}],
  'role': 'user'},
 {'content': [{'toolUse': {'input': {'a': 1, 'b': 1},
                           'name': 'add_w_state',
                           'toolUseId': 'tooluse_add_w_state_975207425'}}],
  'role': 'assistant'},
 {'content': [{'toolResult': {'content': [{'text': "Error: KeyError - 'agent'"}],
                              'status': 'error',
                              'toolUseId': 'tooluse_add_w_state_975207425'}}],
  'role': 'user'},
 {'content': [{'text': 'agent.tool.add_w_state was called.'}], 'role': 'assistant'}]

Additional Context

I am using a custom model object to utilize models from Snowflake Cortex.

Possible Solution

Add agent to invocation state dictionary on line 79 of strands.tools.executors._executor.

Related Issues

No response

[q-maze]

Opened #1213 with a possible fix.