AI agents call wave_list_receipts to retrieve information from Waveapps without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and queries financial transaction data (receipts) without modifying, deleting, or executing external operations. It is a read-only lookup operation with no side effects. Severity is low because exposing financial transaction visibility poses limited risk compared to write/execute operations on the same server.
From the tool's definition Tool name 'wave_list_receipts' and description explicitly state it 'Lists receipt-capture transactions' with no mention of creation, modification, or deletion. GraphQL-backed retrieval operation.
Attacks that exploit this kind of access
Lists receipt-capture transactions for a Wave business. GraphQL-backed; receipts are modelled as transactions with. It is categorised as a Read tool in the Waveapps MCP Server, which means it retrieves data without modifying state.
Register the Waveapps MCP server in PolicyLayer and add a rule for wave_list_receipts: 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 Waveapps. Nothing to install.
wave_list_receipts 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 wave_list_receipts 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 wave_list_receipts. 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.
wave_list_receipts is provided by the Waveapps MCP server (lunaparker/waveapps-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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