Python: Bug: OrchestrationHandoffs() using agent names ignores description #13115

Describe the bug
The examples Handoff Orchestration use agent names (as opposed to passing in the agents themselves).

Please reference: OrchestrationHandoffs::add():
python/semantic_kernel/agents/orchestration/handoffs.py

description=description or target_agent.description or "" if isinstance(target_agent, Agent) else "",

If you don't pass in an agent, then this line just passes "" to self._add()

It looks like there may be similar issues in add_many(). Also, the interface feels awkward taking both list[str | Agent]. This behavior isn't documented anywhere.

To Reproduce
Steps to reproduce the behavior:
Create a handoff using agent names like the examples (not agents). Then just pprint the handoff. You will see the handoff mapping, but the descriptioin is missing.

Expected behavior
I expect the handoffs to include the description passed in during OrchestrationHandoffs initialization.

Screenshots
N/A

Platform

• Language: Python
• Source: [e.g. NuGet package version 0.1.0, pip package version 0.1.0, main branch of repository]
• AI model: gpt-oss120b
• IDE: vscode
• OS: linux

Additional context
Add any other context about the problem here.