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

Annotations already establish readOnly/destructive=false, but the description adds real value beyond them: page size cap of 100, cursor-based pagination mechanics, and the required Cotlet API key with app access. It omits error behavior and rate limits, which keeps it short of a 5.

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?

Front-loaded with the core purpose, which is good, but 'newest first' is stated twice and the status enum is enumerated in the description even though the schema already carries it. Two sentences could be trimmed without losing information.

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 output schema, the description carries the burden of explaining returns and does so ('status, plan, quantity and next billing date'), plus pagination, sorting, and auth prerequisites. An agent has everything needed to call and paginate 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?

Schema description coverage is 100%, so the schema already documents all six parameters, and the description largely repeats the enum values and filter meanings. The one genuine addition is explaining that the returned next_cursor is passed back as the cursor parameter, which compensates slightly for the naming mismatch between description and 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?

States a specific verb and resource ('Subscriptions filtered by customer, status, plan or renewal date') and adds scope details like sort order and the status vocabulary. It is immediately distinguishable from sibling read tools such as get_subscription because it is explicitly a filtered collection.

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?

'Use it to find who is on a plan or whose subscription renews soon' gives concrete usage context that maps to the customer_id, item_price_id and next_billing_before filters. However, it never names an alternative (e.g., get_subscription for a single record) or states when not to use it.

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