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

Annotations are minimal (readOnlyHint=false, idempotentHint=false, openWorldHint=true), providing little behavioral info. The description adds crucial context: the link is tied to this account only, the response names the account (masked email) and instructs to tell the traveller. It is non-idempotent but doesn't detail side effects (e.g., generating a unique link), but given the context, this is sufficient.

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 compact: 3 sentences, front-loading the core action and key constraint (no sign-in needed), then usage conditions and plan details. Every sentence adds value: purpose, behavior, when-to-use, and parameters. No filler.

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?

Given the tool's simplicity (1 parameter, no output schema), the description covers the essential elements: what it does, when to use it, the plan options with pricing, and the behavioral nuance (account-tied link). The only minor gap is not describing the response format fully, but it mentions the masked email. It's complete enough for an agent to call correctly.

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?

The schema has only one parameter (plan) with an enum, so it's fully specified in the schema. The description adds pricing details ($6.9/$39.9) which help the agent communicate, but the parameter semantics are already clear from the enum. Since schema coverage is 0% but the parameter is self-explanatory, the baseline is 3.

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 states the verb (generate) and resource (Paddle checkout link for upgrading THIS account to Plus), and adds a key differentiator: no sign-in needed. It distinguishes itself from sibling tools like create_share_link and create_upload_link by specifying the upgrade context.

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 provides explicit usage conditions: 'Only call when the user explicitly asks to upgrade or after a quota error told you to offer it.' This gives clear when-to-use guidance and implicitly excludes other scenarios. It also specifies the plan parameter options (monthly/yearly) with pricing, helping the agent decide.

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