Python: A2AAgent should default name/description from AgentCard when not explicitly provided #4630

Summary

When constructing an A2AAgent with an agent_card, the name and description parameters must be explicitly passed even though the AgentCard already contains this information. This creates unnecessary duplication:

# Current - redundant
agent = A2AAgent(agent_card=card, name=card.name, description=card.description)

# Proposed - card provides defaults
agent = A2AAgent(agent_card=card)

Current Behavior

In A2AAgent.__init__(), name and description default to None and are passed directly to BaseAgent.__init__(). The agent_card is only used for transport setup (creating the HTTP client). If name/description are not explicitly provided, they remain None on the agent instance - even though the card has them.

Proposed Change

When agent_card is provided and name/description are not explicitly set, A2AAgent.__init__() should fall back to agent_card.name and agent_card.description:

def __init__(self, *, name=None, description=None, agent_card=None, ...):
    if agent_card is not None:
        name = name or agent_card.name
        description = description or agent_card.description
    super().__init__(name=name, description=description, ...)

This is backward compatible - explicit values still take precedence.

Motivation

When using A2AAgent as a participant in GroupChat orchestrations, the agent's name and description are essential for routing decisions. It's natural to expect that passing an AgentCard (which already carries these fields) would be sufficient.