Retrieve a customer record by CUST-NNNNN ID to check account status and refundable balance before issuing a refund.
Returns the customer record for a customer ID in the format CUST-NNNNN, including account status and refundable balance.
| Name | Required | Description | Default |
|---|---|---|---|
| customer_id | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | ||
| Yes | |||
| status | Yes | ||
| currency | Yes | ||
| createdAt | Yes | ||
| customerId | Yes | ||
| refundableBalance | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden; "Returns" implies a read-only lookup, and it names the salient returned fields, which is useful. It does not disclose auth/permission requirements or what happens for an unknown yet well-formed ID, so behavioral disclosure is only partial.
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 sentence that front-loads the action and resource, then appends the useful payload detail. Nothing is padded or redundant.
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?
The tool is simple (one required param, output schema present so return values needn't be spelled out), and the description covers purpose, ID format, and key fields. It omits error/not-found behavior and any routing hint relative to trigger_refund, which for a refund-adjacent lookup leaves a real gap.
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 coverage is 0%, so the description must compensate, and it does partially by stating the CUST-NNNNN format. However, that format is already encoded in the schema's regex pattern, so the description mostly restates structured data without adding meaning about where the ID comes from or how to obtain it.
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?
States a specific verb and resource ("Returns the customer record") plus the ID format and the notable payload fields (account status, refundable balance). It is clear on its own but does nothing to distinguish it from the sibling trigger_refund, which is the obvious adjacent action for a record that exposes a refundable balance.
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 explicit when-to-use, when-not-to-use, or alternative named. The only hint is that the tool is a lookup keyed by customer ID, which leaves the agent to infer that trigger_refund is the follow-up mutation rather than reading it here.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.