Design-First Agents
Design-first agents means defining an AI agent’s contract — its A2A agent card, skills, and expected behavior — before any implementation, then validating that design and turning it into a runnable mock. Instead of coding an agent and documenting it after, you agree on the interface up front, mock it, test it, and only then build the real backing implementation. A²D makes the design the source of truth.
Design-first is the philosophy; mocking AI agents is how you exercise the design. Read them together.
Why design agents first
Agent-to-agent ecosystems break when each team ships an agent and reconciles interfaces later. Designing first prevents that:
- Contract agreement early — consumers and producers align before code.
- Parallel work — clients build against the mock while the agent is implemented.
- Quality shifted left — validate the design against rules before writing logic.
- Fewer integration surprises — the mock is exactly what production will expose.
The design-first agent workflow
- Design the agent card: identity, capabilities, and reusable skills.
- Validate it against organization design rules for consistency.
- Mock its behavior with scenarios so it runs before implementation.
- Test it with suites across environments and track coverage.
- Publish the validated agent card when it is ready.
Design rules keep agents consistent
When many teams design agents, consistency matters. A²D design rules enforce naming, structure, and organizational standards on agent cards before they are published — see Using design rules. This is what makes design-first scale beyond a single team.
Next Steps
- Mock AI agents - Turn the design into a runnable mock
- Creating agent cards - Build the agent card
- Using design rules - Validate the design
- Design-first MCP - The same approach for MCP servers
Agree on the interface first — design, validate, and mock agents before you build them. 🤖