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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description only repeats 'Read only' and does not add behavioral detail such as result size, pagination, or behavior when the contract has no subscribers; a 3 reflects minimum viability with little added context.

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 very short and front-loads the returned resource. 'Read only' duplicates the annotation rather than adding new information, but the overall structure is efficient with no bloat.

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 simple one-parameter read-only list tool, the definition covers the core scope. However, with no output schema and no description of return shape or empty-result behavior, it leaves some gaps that an agent might otherwise need to infer from sibling tools.

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%, so the single contractId parameter is already documented as 'Id from list_contracts.' The description's phrase 'one plan' loosely reinforces the contract scope but adds no format or lookup guidance beyond the schema.

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 returned resource and scope: students subscribed to one plan. However, it does not explicitly distinguish this tool from related siblings such as list_student_subscriptions or list_subscriptions, which also deal with subscription membership.

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 gives no guidance on when to use this tool versus alternatives. The only usage hint is in the schema, where contractId says 'Id from list_contracts,' but the description itself offers no context, prerequisites, or exclusions.

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