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

Annotations already declare this as a read-only operation, so the safety profile is covered. The description adds useful context by listing the returned fields (buyer, amount, status, PDF-sent flag), but it does not disclose pagination, sorting, or any scoping constraints beyond the resource itself.

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 a single, front-loaded sentence with no wasted words. It efficiently names the resource and parenthetically summarizes the key fields, making it easy to scan.

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?

With no input parameters and no output schema, the description does a good job summarizing what the tool returns. It could be slightly more complete by mentioning pagination or result limits, but for a simple zero-parameter read-only list tool it is adequate.

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 tool has zero parameters, so there are no parameter semantics to document; the baseline of 4 applies. The description instead describes returned fields, which is helpful for an agent interpreting the output.

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 resource as one-off purchases of the coach's marketplace workout/diet plans and templates, including the key fields returned. It lacks an explicit verb like 'list' and does not explicitly distinguish itself from siblings such as list_payments or list_my_plans, but the scope is specific enough for an agent to understand what it retrieves.

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?

Usage is implied: an agent can infer this tool is for viewing purchases of marketplace plans. However, the description provides no explicit when-to-use guidance, no exclusions, and no mention of alternatives like list_payments, leaving the agent to infer selection from the resource name alone.

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