# Agent Utilities Public content (free, no key): GET /v1/content/index for links, GET /v1/content for full JSON, or GET /llms-full.txt for the complete text guide. Individual resources: /v1/content/tools/, /v1/content/workflows/, /v1/content/docs/. Public read endpoints allow browser CORS. Tool execution remains metered. 36 bounded tools; GET /v1/tools?category=security&q=scan for discovery and schemas. Prices use integer micro-dollar service credits (1 USD = 1000000 units), or testnet micro-USDC for optional crypto. Read /billing/api/status for live or test credit availability; crypto is a separate testnet-only option. Card credits: GET /billing/api/status. When configured, POST /billing/api/accounts returns one-time API and recovery credentials. Save both privately before checkout. Use Authorization: Bearer on POST /billing/api/checkout with a stable Idempotency-Key UUID, then complete the Stripe Checkout for the mode shown in /billing/api/status. Credit is granted only after a verified webhook. GET /billing/api/balance reads your balance. Tool calls use the same Bearer key and Idempotency-Key: _. Retry the identical ID, tool and body; recovery is ten minutes. These credits only purchase this service. Optional X-Max-Credit-Micro-Usd sets an integer ceiling (0–999999999999) for a new prepaid debit; HTTP 412 rejects a higher price without charging. Existing matching retries create no new reservation and can use zero, which does not undo an earlier debit. Applies to HTTP calls and MCP tools/call. Read creditPriceLimits in /billing/api/status. MCP adapter 0.3.0 caps new debits at startup catalog prices and uses a zero ceiling for its recovery helper. The runnable cart recipe and browser workspace also set ceilings. Older adapter 0.2.1 does not. POST /v1/tools/ with JSON. When configured, unpaid requests get x402 v2 HTTP 402. A buyer needs a funded Circle Gateway testnet balance, the official BatchEvmScheme and our request-binding helper. Ordinary x402 or MCP clients cannot automatically pay this extension. Request binding: read extensions.agent-utilities-request-binding.info.quote from the 402 body. Create the official payment payload, then EIP-191 sign exactly: "Agent Utilities request binding v1\nQuote: \nPayment SHA256: ". Canonical JSON recursively sorts object keys, preserves arrays, no whitespace. Send PAYMENT-SIGNATURE, X-Quote and X-Quote-Signature. See scripts/buyer.ts in the source distribution. Retry the SAME body, quote and signed payload after response loss or settlement_unknown. Never automatically create another authorization. Recovery is ten minutes; encrypted result material is removed on the next minute cleanup. Authorization tombstones remain until one day after payment expiry. Python clients: download the standard-library client from /integrations/python. Prepare a call once with an explicit maximum price and reuse that prepared call for recovery. No Node or MCP process required. Ordinary stdio MCP clients: install the downloadable Node.js adapter from /integrations/mcp. It reads AGENT_UTILITIES_API_KEY from its environment and manages credit retry headers. No wallet is needed for Stripe credits. /mcp supports initialize, tools/list and tools/call over stateless JSON HTTP. tools/call uses the same payment headers. There is no free execution route. Network tools only fetch operator-approved HTTPS hosts. Secret checks are fixed heuristics and do not establish safety.