Validates an official promotional discount coupon code for eSIM checkout.
| Name | Required | Description | Default |
|---|---|---|---|
| code | Yes | The coupon code to validate (e.g. WELCOME10). | |
| packageCode | No | Optional eSIM package code to check applicability for. |
| Name | Required | Description | Default |
|---|---|---|---|
| content | No | ||
| isError | No |
Changes observed during successful MCP inspections.
Input schema / properties / packageCode / descriptionPrevious value: -"The eSIM package code to check applicability for."New value: +"Optional eSIM package code to check applicability for."Input schema / requiredPrevious value: -[
- "code",
- "packageCode"
-]New value: +[
+ "code"
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds the useful constraint that only 'official promotional' codes are honored, but says nothing about invalid-code behavior, rate limits, or applicability checks.
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 front-loaded sentence with no filler or redundancy. Every word contributes to identifying the operation.
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?
For a simple two-parameter read-only validator with a full-coverage schema and an output schema covering return values, the description is nearly sufficient. It could mention what an invalid result implies, but that is reasonably delegated to the output schema.
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 100%, so both parameters are already documented in the schema; the description adds only the qualifier that codes are 'official promotional' ones. Baseline 3 is appropriate when the schema carries parameter semantics.
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 (validates) and resource (coupon code) with domain scope (eSIM checkout), which cleanly separates it from get_available_coupons. It does not explicitly name a sibling, so it falls short of a 5.
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?
The phrase 'for eSIM checkout' implies the usage context, but there is no explicit when-to-use versus get_available_coupons (which lists codes) or any prerequisite/ordering guidance. Usage is inferred rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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