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

Annotations cover the safety profile (readOnlyHint=false, openWorldHint=true, destructiveHint=false). The description adds real context beyond that: default confirmation per call with an opt-out, an explicit human-confirmation requirement because it reaches recipients, and the API-key scope needed. Lacks any note on rate limits or delivery failure behavior.

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?

Purpose is front-loaded and each clause is actionable (prerequisite, confirmation default, recipient warning, auth). Slight redundancy in restating 'the buyer gets the receipt again' across two sentences, which could be trimmed.

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 one-parameter, no-output-schema tool, the description covers purpose, ordering relative to a sibling, confirmation behavior, external-recipient risk, and authentication. Nothing an agent needs to invoke it correctly is missing.

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% and the single order_id parameter is documented there ('Order ID from list_orders'). The description adds only indirect navigation context via the reset_download_credits prerequisite, so the schema does the heavy lifting.

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 (email/resend) and resource (the receipt and download link to the buyer) plus the effect (buyer gets the receipt again). An agent can distinguish it from payhip_get_order and payhip_reset_download_credits without opening schemas.

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?

Explicit when-to-use and prerequisite routing: 'If the buyer ran out of download attempts, call reset_download_credits first.' It also names the condition that requires extra care (reaches other people: confirm with the user before each call), leaving little to inference.

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