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

Annotations already declare read-only, non-destructive and open-world, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: output is JSON, certain categories trigger a hard failure on non-Pro plans, and a Cotlet API key with app access is required. It does not describe pagination or result shape in detail, keeping 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?

Four compact sentences, front-loaded with the core purpose and ending with prerequisites. The first sentence and second sentence overlap ('Numbers from Stats & Reports for a period' vs. 'Returns the numbers of one Stats & Reports category for a date range'), a minor redundancy that keeps it from a 5.

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?

No output schema exists, so the description must carry the return story; it does so minimally ('as JSON', 'the numbers'). Combined with the plan-tier failure behavior and auth requirement, an agent has enough to invoke correctly, though the shape of the returned numbers per category remains unspecified.

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% and each parameter (category, from, to) is already documented in the schema, including the enum. The description's category list and Pro-tier note restate what the schema says rather than adding syntax or format detail, so the baseline 3 applies.

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 — returns the numbers of one Stats & Reports category for a date range — which no sibling tool does (siblings cover appointments, clients, services, staff). An agent can distinguish it from booksy_list_appointments or booksy_get_appointment without opening a schema.

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?

Gives clear contextual guidance: which categories are available on Booksy Biz Lite vs. Pro, and that the call fails for other plans. It doesn't name an alternative tool to use instead when the plan is insufficient, but there is no overlapping sibling, so the practical routing guidance is complete.

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