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Nomos Budget Check API
x402
Nomos Budget Check API is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).
Validates whether an autonomous agent has sufficient budget and authorization to proceed with a requested spend, returning a risk assessment and approval decision.
Price / call$0.02
Success—
StatusUnknown
How this service works
Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend.
Output
Returns a JSON object containing a risk_score (numeric), risk_level (e.g. 'low', 'medium', 'high'), a flags array listing any policy violations or concerns, and metadata including the product name and network identifier (e.g. 'eip155:8453' for Base). If the request exceeds the auto_approval_threshold or per_transaction_limit, the assessment will indicate a REVIEW or DENY decision.
Example use cases
Pre-spend guard for DeFi trading agent
“Before agent 'defi-agent-01' swaps tokens, check if its 8.50 USDC requested spend is within policy — it has 200.00 USDC remaining budget and a per-transaction limit of 15.00 USDC, purpose is 'defi:swap', currency USDC.”
Expense approval for enterprise AI agent fleet
“Our enterprise agent 'procurement-agent-corp' wants to spend 450.00 USDC on 'vendor:invoice-pay' — check if it's within budget given 1000.00 remaining and a 500.00 per-transaction limit, and flag for review if it exceeds 400.00.”
Micro-payment risk assessment for API-calling agent
“Agent 'api-scraper-99' is about to pay 0.02 USDC for an API call (purpose: 'api:data-fetch'), with 5.00 USDC left in its budget and a 0.50 per-transaction cap — confirm it's low risk and approved.”
Technical details
Endpoint
POSThttps://base-agent-preflight.bytoken2023.workers.dev/x402/v1/policy/budget-checkWhen to prefer
Use this endpoint when an autonomous agent needs a lightweight, pay-per-use preflight authorization check before executing a financial transaction, particularly when enforcing per-transaction limits, remaining budget constraints, and risk thresholds in USDC/USDT/USD. Prefer this over static rule engines when you need a dynamic risk score with flag-level detail. Best suited for agentic systems on Base/EVM chains already integrated with x402 payment infrastructure.
Side effects
- Missing required query parameters (agent_id, currency, requested_amount, remaining_budget, per_transaction_limit, purpose) returns a 400 validation error
- Invalid parameter format (e.g. agent_id with special characters, non-numeric amount) rejected by pattern validation
- Payment of $0.02 USDC not received results in 402 Payment Required response
- Idempotency key collision may return cached prior decision rather than fresh evaluation
- Requested amount exceeding per_transaction_limit returns high risk or DENY flag
- Service unavailability on Cloudflare Workers edge returns 503
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"network": "eip155:8453",
"product": "nomos-budget-check",
"assessment": {
"flags": [],
"risk_level": "low",
"risk_score": 0
}
}
}Tags
x402
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