list_user_invoices
AI agents call list_user_invoices to retrieve information from Nebulablock without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Listing invoices is a read-only operation that retrieves historical financial records. While the data concerns financial transactions, the tool itself does not move money, modify accounts, or create obligations—it only queries existing invoice data. This places it in the Read category with low severity, as invoice retrieval has minimal blast radius for accidental misuse by an AI agent.
From the tool's definition Tool name 'list_user_invoices' indicates retrieval of invoice records with the 'list' prefix, which is a query/retrieval operation.
Attacks that exploit this kind of access
list_user_invoices. It is categorised as a Read tool in the Nebulablock MCP Server, which means it retrieves data without modifying state.
Register the Nebulablock MCP server in PolicyLayer and add a rule for list_user_invoices: 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 Nebulablock. Nothing to install.
list_user_invoices 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 list_user_invoices 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 list_user_invoices. 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.
list_user_invoices is provided by the Nebulablock MCP server (nebula-block-data/nebulablock-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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