List Firefox Relay custom-domain masks when available.
AI agents call relay_list_domain_masks to retrieve information from Firefox Relay without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays existing Firefox Relay domain masks. It performs a read-only query operation without creating, modifying, deleting, or executing any actions. The blast radius of misuse is minimal — an attacker gains visibility into existing masks but cannot alter them or cause financial harm.
From the tool's definition Tool name 'relay_list_domain_masks' and description 'List Firefox Relay custom-domain masks' — list indicates retrieval/querying operation with no modification or side effects.
Attacks that exploit this kind of access
List Firefox Relay custom-domain masks when available. It is categorised as a Read tool in the Firefox Relay MCP Server, which means it retrieves data without modifying state.
Register the Firefox Relay MCP server in PolicyLayer and add a rule for relay_list_domain_masks: 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 Firefox Relay. Nothing to install.
relay_list_domain_masks 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 relay_list_domain_masks 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 relay_list_domain_masks. 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.
relay_list_domain_masks is provided by the Firefox Relay MCP server (nazar256/firefox-relay-mcp). 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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