Check if a domain is available for purchase and get its price. Always call this before buying. After showing the price, ask the user two things before proceeding: 1. Confirm they want to purchase at that price. 2. Which payment method they prefer: - "card" / "Stripe" → call buy_domain (opens Stri...
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AI agents call check_domain to retrieve information from Instadomain without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though check_domain only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"check_domain": {}
}
}See the full Instadomain policy for all 12 tools.
These attack patterns abuse exactly the kind of access check_domain gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Check if a domain is available for purchase and get its price. Always call this before buying. After showing the price, ask the user two things before proceeding: 1. Confirm they want to purchase at that price. 2. Which payment method they prefer: - "card" / "Stripe" → call buy_domain (opens Stripe checkout in browser) - "crypto" / "USDC" / "x402" → call buy_domain_crypto (autonomous USDC payment, no browser; requires Coinbase Payments MCP or another x402 wallet) - "MPP" / "agent pay" → call buy_domain_mpp (Stripe agent payments via Shared Payment Token, no browser) If the user has Coinbase Payments MCP configured in their session, suggest crypto as the default. Otherwise default to buy_domain (Stripe). Args: domain: The full domain name to check (e.g. "coolstartup.com"). Returns: Dict with availability status, price in cents, and formatted price.. It is categorised as a Read tool in the Instadomain MCP Server, which means it retrieves data without modifying state.
Register the Instadomain MCP server in PolicyLayer and add a rule for check_domain: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Instadomain. Nothing to install.
check_domain is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the check_domain rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for check_domain. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
check_domain is provided by the Instadomain MCP server (https://instadomain.fly.dev/mcp/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 12 Instadomain tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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