AI-First API Design

Historically, we've designed APIs with human developers in mind. But AI agents don't consume APIs like humans do. They need explicit signals, clear context, and structured information to make intelligent decisions. This isn't just about making our APIs more complex, it's about making them more context aware. The future of API design is about creating interfaces that enable true machine-to-machine communication.

Let me show you what I mean:

{
  "status": "error",
  "message": "Email not verified"
}

This might work for a human, but it's less practical for an AI agent. Here's how an AI-friendly version might look:

{
  "status": "email_verification_required",
  "remediation": "Ensure the email provided is a valid email address",
  "recommendedNextAction": "verify_email",
  "availableActions": ["resend_verification", "update_email"],
  "actionPriority": "high"
}

See the difference? One tells you what's wrong, the other tells you what to do about it. Without knowing your entire API spec, an AI will have to guess what action to take next. By providing context about what could be next actions we handhold the AI to ensure it finds the path through your API.

Semantic Precision

One of the most critical aspects of AI-first APIs is semantic precision. AI agents need crystal-clear definitions and relationships:

{
  "userStatus": {
    "type": "enum",
    "value": "ACTIVE",
    "allowedValues": ["ACTIVE", "SUSPENDED", "PENDING"],
    "description": "Current state of user account access"
  },
  "profileCompletion": {
    "type": "integer",
    "value": 85,
    "range": {"min": 0, "max": 100},
    "unit": "percentage"
  }
}

This explicit typing eliminates ambiguity. This will for sure increase your response size, but again allows AI agents to consume your API as intended.

Beyond Status Codes

AI agents are really good at chain-of-thought reasoning. Providing them with breadcrumbs will enable them to make better choices.

{
  "orderStatus": "payment_processing",
  "contextChain": {
    "previousStates": ["cart_created", "payment_initiated"],
    "dependentOperations": ["fraud_assessment"]
  }
}

The Cost of Computation

If your underlying system relies on a 3rd party system based on consumption model, you might need to expose some of the resource cost to make the AI agent aware of the implication of their actions.

{
  "operationCost": {
    "creditsCost": 5,
    "estimatedDuration": "2s"
  },
  "rateLimits": {
    "current": 98,
    "limit": 100
  }
}

Uncertainty Handling

APIs should have confidence levels, offer alternative options, and specify triggers for human intervention when needed.

{
  "prediction": "fraudulent_transaction",
  "confidence": 0.87,
  "alternatives": [
    {"prediction": "legitimate_transaction", "confidence": 0.12}
  ],
  "requiresHumanReview": true
}

Conclusion

I think we just see the beginning of AI-first API design. More and more products will incorporate AI agents. As such we as providers of the underlying building blocks it is in our best own interest to ensure our APIs are not just consumable but also AI-agent friendly.