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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds useful domain semantics: one-off vs recurring subscriptions, startDate as the renewal/due date, and paymentDate as the first money-leaves date that repeats on cadence. This is meaningful context beyond the structured fields, though it doesn't cover pagination or ordering – minor for a simple read-only list.

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?

Three sentences: purpose, one-off clarification, and date semantics. Each sentence earns its place, and the main verb+resource is front-loaded. There is no filler or redundancy.

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 read-only list with one optional parameter, full schema coverage, and an output schema present, the description covers purpose, filtering, and output semantics. Nothing an agent needs in order to call 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%; the status parameter is fully documented in the schema, including the omission behavior. The description only repeats 'Pass status to filter to one,' adding no new parameter-level meaning beyond the schema. The baseline of 3 applies because 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?

The description opens with 'List tracked subscriptions' – a specific verb, resource, and the returned fields (fee, renewal schedule, payment date, status). This clearly distinguishes it from subscription mutation tools like create_subscription and update_subscription. There is no ambiguity about what the tool does.

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 tells the agent how to filter with 'Pass status to filter to one,' and the schema reinforces that omitting it returns all statuses. It doesn't explicitly name alternatives, but the sibling list_* tools make resource distinctions obvious. No misleading guidance is present.

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