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

Annotations already cover the read-only safety profile, but the description adds real behavior: the enriched aggregate output, the auth requirement ('Needs the user's Cotlet API key with access to this app'), and the non-obvious 'Cancelled (still active)' semantics. It stops short of describing pagination or result caps.

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 and generally readable, but the first sentence and second sentence restate the same thing ('count, monthly recurring revenue and yearly revenue' then 'the number of matches and their monthly recurring revenue and yearly revenue'), which is wasted repetition in a short description.

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 describing return values, and it does list them (subscriptions, match count, MRR, yearly revenue) plus the auth prerequisite. Minor gaps remain around pagination and ordering, but nothing essential for calling it 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% so the baseline is 3, but the description adds meaning beyond the schema by explaining that 'Cancelled (still active) means the customer cancelled renewals but has access until the last paid date' — a definition the enum list alone does not convey.

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?

Names a specific verb and resource ('List subscriptions') and goes further by declaring the enriched payload (match count, MRR, yearly revenue), which distinguishes it from plain list tools like thrivecart_list_transactions. An agent can tell at a glance what it returns and why it differs from siblings.

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?

Provides an explicit use case ('see how much paused or overdue subscriptions cost you') that tells the agent when this tool is worth calling. It does not, however, name or exclude alternatives such as thrivecart_cancel_subscription or pause_subscription, leaving sibling routing implicit.

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