Instead of injecting tool definitions as text into the system prompt,
HermesA2AExecutor now accepts a tools: list[dict] | None constructor
parameter containing OpenAI-format tool definitions and forwards them
via the native tools= parameter on chat.completions.create().
Empty list / None rule: when tools is falsy, the tools key is omitted
from the API call entirely — never sent as tools=[] — so providers
that reject an empty tools array don't return a 400.
Tool-call response handling: when the model returns finish_reason
"tool_calls" with no text content, the executor serialises the call
list as a JSON string and enqueues it as the A2A reply. This keeps
the executor thin (single API call per turn, no ReAct loop) while
surfacing function-call intent in a structured, parseable format.
Changes:
- HermesA2AExecutor.__init__: new tools kwarg; stored as self._tools
(copy; mutating the input list has no effect)
- execute(): builds create_kwargs dict and conditionally adds tools=
only when self._tools is non-empty; handles tool_calls response
- Module docstring: new "Native tools (#497)" section with schema
reference and edge-case explanation
Tests (12 new, 47 total in hermes test file, 1002 total suite):
- tools stored correctly in constructor (copy, None, [], non-empty)
- non-empty tools forwarded as tools= in API call
- multiple tools all forwarded
- empty list ([] and None and default) → tools key absent from call
- model tool_call response → JSON-serialised list as A2A reply
- multiple tool_calls → all in JSON reply
- text content present → text wins over tool_calls
Closes#497
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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