Short answer
x402 agent spend limits define how much an agent may spend when a service uses payment-required requests. The policy should cover request size, daily budget, token choice, retry behavior, recipient scope, and what happens when a limit is reached.
When this matters
- An agent pays per request for data, inference, API calls, or gated content.
- A service wants to accept agent payments without exposing customers to runaway spend.
- A wallet team needs a clear limit screen before enabling automated payments.
- A project wants webhook alerts when an agent approaches or exceeds a budget.
Operating steps
- Define the request category, expected unit cost, allowed token, and destination service.
- Set per-request, hourly, and daily budgets that match the real cost envelope.
- Add retry rules so failed payments do not silently multiply spend.
- Attach revocation rules to stop the agent when the service, token, or contract changes.
- Record every limit decision as audit evidence for support and governance.
Common risks
- Per-request costs can spike if the agent loops or retries after a service error.
- A missing recipient allowlist can let a payment policy apply to the wrong contract.
- Payment prompts can be accepted too broadly when users do not see the total budget.
- x402-style flows need both wallet policy and product-level rate controls.
How Web3Agent Permit fits
Web3Agent Permit models x402 spend policy, monitors payment attempts, and alerts teams when an agent leaves the approved payment envelope.