Retrieve a customer's card charges and see any refunds already applied by providing their email address.
List a customer's card charges, with any refunds already made.
| Name | Required | Description | Default |
|---|---|---|---|
| justification | No | Why you are making this call, in one sentence. The person who approves it reads this; some calls need it. | |
| customer_email | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.13.0Input schema / properties / justificationAdded value: +{
+ "description": "Why you are making this call, in one sentence. The person who approves it reads this; some calls need it.",
+ "type": "string"
+}v0.3.8Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It does disclose one genuine behavioral detail beyond the name — that returned charges include any refunds already applied — which is useful. However it says nothing about permissions, pagination, or approval requirements, which the 'justification' parameter in the schema implies are relevant.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single efficient sentence with the resource and scope front-loaded and zero filler. It is appropriately sized for a simple list operation, though it is arguably too terse to earn a 5.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
An output schema exists, so return values need not be explained, but with zero annotations, an undocumented required parameter, and no mention of approval or auth context despite an approval-oriented 'justification' field, the definition leaves material gaps for a payments-related tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is only 50%: customer_email is undocumented in the schema, and the description never clarifies its format or how it is matched. The description adds no meaning to either parameter, so it fails to compensate for the coverage gap.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a clear verb (List) and specific resource (a customer's card charges), and adds a scope qualifier ('with any refunds already made'). It does not explicitly differentiate itself from siblings like payments_refund or payments_transfer, but the read-oriented framing makes its role reasonably inferable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no guidance on when to use this tool versus alternatives such as payments_refund or crm_find_customer, nor any prerequisites (e.g., customer must exist, approval may be required). The agent is left to infer usage entirely from the name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.