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

Annotations declare non-readOnly, non-destructive, open-world, non-idempotent. The description usefully adds what the annotations cannot: nothing is charged at generation time, payment happens later in the user's browser, and a user-intent gate applies. It does not warn that repeated calls produce distinct links, which is the one behavioral gap.

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?

Four short sentences, front-loaded with the action and outcome, then the no-charge clarification, then the hand-off instruction, then the precondition. Every sentence carries distinct information.

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-value detail is not needed, and the description covers purpose, safety, and the user-intent gate. The only omission is auth context (the conditional apiKey, already documented in the schema) and duplicate-link behavior.

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 100%, including the enum values with pricing, so the schema already carries parameter meaning. The description only implies the Pro target and adds no tier-selection or apiKey/authorization context beyond it. Baseline 3 is appropriate.

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 (Generate) plus resource (Paystack checkout link) and the business outcome (upgrading to Pro / unlimited card views). It is clearly distinguishable from siblings like get_subscription or create_shareable_link.

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?

Gives an explicit precondition: 'Only call this after the user has said they want to upgrade,' plus downstream guidance to hand the link to the user. It does not name alternative tools or describe what to do if the user is already Pro, so it stops short of full routing guidance.

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