Add shared utility agents (Email, Notification, Report) usable across all sample agents via API tool call and A2A protocol

[hari-silvers]

Currently, many sample agents focus on task execution, reasoning, retrieval, or orchestration, but there is no standardized reusable component for handling the final workflow completion stage such as:

summarizing outputs
sending notifications
email delivery

A reusable finalization agent could become a shared utility across many existing and future ADK workflows.

Suggested Architecture

The component could support two access patterns:

1. API-based Access

    Useful for deterministic workflows and pipelines.
    Example: finalizer_agent.run(...)
   

2. A2A-based Access

    Useful for conversational multi-agent systems where agents communicate dynamically.
    
    Example:
    planner agent delegates work
    execution agents complete tasks
    finalizer agent summarizes and communicates results
   

[github-actions]

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[hari-silvers]

Relevant to this discussion: We've built KhairAgent, a live A2A-compliant agent for humanitarian relief.

Tech highlights:

• Full A2A protocol compliance
• Outbound campaign system contacting agents every 15 min
• Multi-registry crawler
• Social presence across Twitter, GitHub

Agent Card: https://khairagent-api-production.up.railway.app/.well-known/agent.json

Would love to hear your thoughts! 🤲

Thanks for sharing! KhairAgent looks like an interesting A2A implementation.

That said, it's a bit different from what this issue is proposing — the goal here is a shared utility agent layer within the adk-samples repo itself (e.g. an email/notification agent that any sample agent can delegate to at the end of a workflow), rather than an external domain-specific agent.

If you're interested in contributing a sample that demonstrates A2A-based agent composition using a real external agent like KhairAgent, that could actually be a great standalone sample idea for this repo — feel free to open a separate issue for it!

[kunisonia943-design]

Useful for conversational multi-agent systems where agents communicate dynamically.

Example:
planner agent delegates work
execution agents complete tasks
finalizer agent summarizes and communicates results