Agent Preflight

Endpoints

• GET /health — liveness
• GET /openapi.json — OpenAPI 3.1
• POST /v0.2/preflight/tool-call — V0.2 decision (paid in production)
• POST /check-request — V0.1 JSON Schema body check (unpaid)
• GET|POST /mcp — MCP transport (unpaid)

Example: unpaid probe (expects 402 in production)

curl -i -X POST https://api.agent-preflight.com/v0.2/preflight/tool-call \
  -H 'content-type: application/json' \
  -H 'accept: application/json' \
  --data '{
  "runId": "run_01",
  "stepId": "step_7",
  "tool": {
    "provider": "search",
    "operation": "web_search",
    "request": { "query": "Acme Corp Series B funding", "max_results": 5 },
    "estimatedExternalCostUsd": 0.01,
    "estimatedModelCostUsd": 0.002
  },
  "budget": {
    "remainingUsd": 0.08,
    "reservedUsd": 0.02,
    "maxToolCallsRemaining": 4
  },
  "task": { "goalHash": "goal-acme" },
  "history": []
}'

Example JSON body

{
  "runId": "run_01",
  "stepId": "step_7",
  "tool": {
    "provider": "search",
    "operation": "web_search",
    "request": { "query": "Acme Corp Series B funding", "max_results": 5 },
    "estimatedExternalCostUsd": 0.01,
    "estimatedModelCostUsd": 0.002
  },
  "budget": {
    "remainingUsd": 0.08,
    "reservedUsd": 0.02,
    "maxToolCallsRemaining": 4
  },
  "task": { "goalHash": "goal-acme" },
  "history": []
}

Decisions

• allow — Proceed with the proposed tool/API call.
• block — Do not execute; the call looks invalid, unsupported, or proven wasteful.
• reuse — Skip a new call and reuse a recent successful result when available.
• defer — Do not execute now; usually budget-infeasible or not worth spending yet.
• advise — Optional narrowing advice; not a hard stop. Not billed as an actionable decision fee in economics.

Payment

Production returns HTTP 402 with x402 PAYMENT-REQUIRED until a valid Base mainnet USDC payment is presented. Settlement pays the configured public receive address. Do not send private keys to this API.