AI agents call get_inbox to retrieve information from X402mail without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves inbox metadata (address and counts) with no side effects or data modification. It is a read operation. While it involves a small financial cost (~$0.001 USDC), the tool itself does not move money or commit financial obligations—it only queries data. The cost is incurred by the user calling the tool, not initiated by the tool's logic.
From the tool's definition Tool name 'get_inbox' and description 'Get your inbox address and message counts' indicate retrieval of account information without modification.
Attacks that exploit this kind of access
Get your inbox address and message counts. Costs ~$0.001 in USDC. It is categorised as a Read tool in the X402mail MCP Server, which means it retrieves data without modifying state.
Register the X402mail MCP server in PolicyLayer and add a rule for get_inbox: 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 X402mail. Nothing to install.
get_inbox 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 get_inbox 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 get_inbox. 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.
get_inbox is provided by the X402mail MCP server (muzsailajos/x402mail). 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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