Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The annotations include readOnlyHint=true, but the description adds critical nuance by stating that the default does not increment uses and that there is an optional side-effect parameter. This is beyond the annotation and clarifies that the read-only hint applies to the default call. The REST endpoint is also disclosed, aiding expectation-setting.

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?

The description is exactly two sentences, front-loaded with the primary action and result. The REST endpoint is a concise detail, and there is no redundant or filler content.

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 straightforward verification tool with three well-documented parameters and a read-only annotation, the description covers the core behavior and return value. It could be more explicit about what 'purchase details' includes, but the absence of an output schema is not a critical gap given the simple nature of the operation.

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%, with all three parameters fully described including default values. The description itself adds no new parameter information, just reinforces the default behavior of increment_uses_count. This meets the baseline for high schema coverage but does not exceed 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?

The description clearly identifies the tool as verifying a license key for a product, checking validity and returning purchase details. This specific verb+resource combination distinguishes it from sibling tools like gumroad_disable_license or gumroad_get_sale. The added note about no side effect by default further differentiates it from usage-incrementing actions.

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 description makes the primary use case obvious (verification/validation) and adds context about the default behavior (no increment), implying when to use the tool vs. passing increment_uses_count=true. However, it does not explicitly name alternative tools or state when not to use this tool, so it falls short of full usage guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.