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

Annotations already establish readOnlyHint=true and openWorldHint=false, so safety is covered. Beyond that, the description discloses the date-window constraint and that results mirror the live booking page, which is genuinely useful behavioral context for trusting/using the output.

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?

Two dense sentences with no filler, and the core purpose is front-loaded ahead of the format and range constraints. The phrase 'at most a couple of weeks' is informal and slightly vague, but the wording is otherwise efficient.

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?

An output schema exists, so return values need not be described, and annotations cover the read-only profile. What an agent needs for a 4-required-parameter call is mostly present except for the slug parameter, which is left to inference.

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?

The schema has 0% description coverage across 4 parameters, so the description has to carry them. It adds real meaning for service_id (from get_kaio_business), start_date/end_date (YYYY-MM-DD format) and the span limit, but says nothing about slug, leaving one parameter entirely unexplained.

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 resource and result: free time slots for one service of a Kaio business, and clarifies these are the same slots the public booking page shows. It names the sibling get_kaio_business as the source of the service id, so an agent can separate it from book_kaio_appointment without opening schemas.

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?

It provides a useful prerequisite (service id comes from get_kaio_business) and a practical calling constraint (at most a couple of weeks per call), but never states when to use this versus book_kaio_appointment or what conditions make it inappropriate. Usage is implied rather than explicit.

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