Tool calling & argref changes

[sidnarayanan]

These are a set of changes to tool call handling and argref_by_name that I found to help reduce agent failure rates.

Tool calling:

• Simplify the returned Message to only be the string representation of an exception, if one is raised and handle_exc=True. The old message (a) leaked implementation details and (b) prevented us from using exceptions for control flow in tools.

argref_by_name:

• If we have def func(a: list[int]), now func(a='foo,bar') is supported.
• If a string was passed as a kwarg, and the string was not found in the state, then we'd pass the string directly as an argument. This was too ambiguous for agents - it is more stable to force a kwarg to either always or never be argref'd

FWIW - I think we should drop *args in argref_by_name methods, since ToolRequestMessages only support kwargs anyway. Would simplify the code significantly.

[whitead]

Hi @sidnarayanan - one issue is in the design PCR, sometimes you need to pass the name of an enzyme. We can change that method to accomodate, but that flexibility for passing in a string or keyname

[jamesbraza]

Let's keep the above logger_msg, but just change the wording from Failed to execute tool call to something like Encountered Exception during tool call.

The reason is:

• Sometimes people don't put a message inside of a raise (e.g. raise ValueError is valid)
• Sometimes people don't state in the message if it's a failure or not

[sidnarayanan]

Done. I'm keeping logger_msg separate above, since we report a bit more info (exception type, tool name).

[sidnarayanan]

@whitead I see, let me think this through

[whitead]

@sidnarayanan I can just change that function to have another set of arguments - enzyme_overhang - for example.

[jamesbraza]

Suggested change

	logger_msg = f"Encountered exception during tool call for tool {tool.info.name}: {exc!r}"
	logger_msg = f"Encountered exception during tool {tool.info.name}: {exc!r}"

[sidnarayanan]

during tool sounds odd - it's during a tool call

[sidnarayanan]

Per offline discussion, will modify design_primers to conform to these changes.

[jamesbraza]

Nice work!