Check whether an IPv4 address (or a domain
AI agents call blacklist_check to retrieve information from Domain Security without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves blacklist status information about an IP or domain. This is a read-only operation that queries external data sources (blacklist registries) without modifying, deleting, or executing anything. The blast radius of misuse is low—an agent might look up incorrect addresses or spam legitimate entities with concern, but no data is actually modified or operations triggered on the target.
From the tool's definition Tool name 'blacklist_check' and context indicate it 'Check[s] whether an IPv4 address (or a domain' is listed on blacklists. This is a query/lookup operation with no side effects.
Attacks that exploit this kind of access
Check whether an IPv4 address (or a domain. It is categorised as a Read tool in the Domain Security MCP Server, which means it retrieves data without modifying state.
Register the Domain Security MCP server in PolicyLayer and add a rule for blacklist_check: 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 Domain Security. Nothing to install.
blacklist_check 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 blacklist_check 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 blacklist_check. 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.
blacklist_check is provided by the Domain Security MCP server (ortamarco/domain-security-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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