upload_receipt · CoupleHub MCP Server MCP: Risk & Policy

WHAT IT DOES

What upload_receipt does on CoupleHub MCP Server

AI agents use upload_receipt to create or update resources in CoupleHub MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your CoupleHub MCP Server environment.

WHY IT NEEDS A POLICY

Why upload_receipt needs a policy

This tool creates a new receipt entry by uploading an image, which is a reversible write operation. While it stores data, uploading a photo does not execute arbitrary code, delete data, or move money. The operation can be undone by deleting the receipt. Severity is low because the blast radius of misuse is limited to unnecessary receipt clutter in a meal-planning application, with no financial or destructive impact.

From the tool's definition Tool name 'upload_receipt' and description 'Upload photo as base64. Returns receipt_id' indicate creation of a new receipt record in the system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

upload_receipt Rate-limited

upload_receipt stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "upload_receipt": {
      "limits": [
        {
          "counter": "upload_receipt_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches CoupleHub MCP Server, so you can run agents against it safely.

FAQ

Questions about upload_receipt

What does the upload_receipt tool do? +

RECEIPT STEP 1. Upload photo as base64. Returns receipt_id. It is categorised as a Write tool in the CoupleHub MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on upload_receipt? +

Register the CoupleHub MCP Server MCP server in PolicyLayer and add a rule for upload_receipt: 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 CoupleHub MCP Server. Nothing to install.

What risk level is upload_receipt? +

upload_receipt is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit upload_receipt? +

Yes. Add a rate_limit block to the upload_receipt 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.

How do I block upload_receipt completely? +

Set action: deny in the PolicyLayer policy for upload_receipt. 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.

What MCP server provides upload_receipt? +

upload_receipt is provided by the CoupleHub MCP Server MCP server (uczesieweba/couplehub-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.