Agent Preflight
Decide before you spend a tool call.
Agent Preflight lets an agent check a planned tool call before spending on it. Send the call you are about to make (a supported search or browse request) with your budget and recent history; get back allow, block, reuse, defer, or advise.
- It does not run your tool. No searches, no page fetches, no results. You decide and execute.
- Call:
POST https://api.agent-preflight.com/v0.2/preflight/tool-call - Price: $0.002 USDC per paid POST via x402 on Base mainnet (
eip155:8453).
Agents: request this page with Accept: text/markdown, or read /llms.txt and the Agent Skill.
When to call it
- Before a supported metered call when a local check is insufficient and plausible benefit exceeds the consultation cost.
- When you have recent tool history and want duplicate / retry detection.
- When remaining budget may not cover the estimated external cost.
What it evaluates
- Tool provider/operation and request shape (supported:
search:web_search,browse:fetch). - Estimated external and model costs vs remaining budget.
- Optional history fingerprints for reuse / terminal retry caps.
- Optional capabilities such as reuse and scope reduction.
Decisions
allow— No rule found waste; the caller decides whether to execute. Not a success guarantee.block— Inspect the reason: invalid request or terminal retry cap. Unsupported operations instead receive advisory abstention.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 scope advice; payload unchanged. Paid HTTP consultations still cost $0.002.
Production endpoint and price
POST https://api.agent-preflight.com/v0.2/preflight/tool-call
$0.002 USDC per HTTP POST via x402 on Base mainnet (eip155:8453) when payment is configured (production is configured for paid collection). Unpaid requests receive 402 with a PAYMENT-REQUIRED header.
POST /check-request and MCP /mcp remain unpaid. A billable HTTP POST is separate from whether a decision is economically “actionable.”
Privacy
Analytics correlate runs using one-way hashes of run and step IDs. Request bodies, schemas, URLs, and raw run/step identifiers are not written to Analytics Engine points.