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

Annotations already declare readOnly/openWorld/non-destructive, so the safety profile is covered. The description adds meaningful context beyond that: the auth requirement ('Needs the user's Cotlet API key with access to this app'), the start-order sort, and that get_appointment fills in remaining detail. Pagination via cursor is implied but not explained.

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-loads the resource and scope, then the narrowing option and return fields. Slightly redundant: the field list ('client, service, staff, time and status') is restated in the later sentence about item contents.

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 usefully summarizes the returned fields and points to get_appointment for the rest, and it discloses the API-key prerequisite. Complete enough to invoke correctly, though pagination behavior for the cursor parameter is left implicit.

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 from/to, staff_id, and cursor are already documented. The description reinforces the date range and single-staff usage but adds no format or syntax detail beyond the schema, so the baseline of 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 ('Lists appointments from your Booksy calendar') scoped to a date range and ordered by start time. It explicitly distinguishes itself from the sibling get_appointment, which 'returns the rest', so an agent can separate the two without opening either 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 usage context: pass a date range, and 'limit it to one staff member to see a single calendar' when a single staff view is wanted. It does not state when NOT to use this tool or name alternatives beyond get_appointment, so it falls short of full when/when-not routing.

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