Why it matters

Seeing concrete examples helps design your own agents. The protocol is generic; the patterns give shape to production use.

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The architecture

Routing agent pattern: user agent receives request, consults capabilities of specialist agents, delegates to best-fit.

Chain pattern: task → agent A → agent B → agent C. Each processes and hands off.

Common A2A patternsRouting agentpicks specialistSpecialist chainsequential handoffsCross-org collabOAuth-mediatedCombinations: routing agent chains across orgs, each org's agents use internal routing
A2A pattern examples.
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How it works end to end

Cross-organization: OAuth-mediated. User authorizes agent to call another org's agent on their behalf.

Multi-round: task can go back and forth via input_required state. Agent asks user for missing info.

Parallel: routing agent invokes multiple specialists concurrently, aggregates results.