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

Annotations already declare readOnlyHint=true, destructiveHint=false, so the safety profile is covered. The description adds genuinely new context: the operation requires the user's Cotlet API key with access to this app, an auth prerequisite not available in the structured fields. It does not cover pagination or error behavior, keeping it at a 4.

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?

The first two sentences are near-duplicates ('One appointment: services, staff, price, client and notes' vs 'Returns one appointment with its services, staff member, price, client and internal notes'), which wastes space. The auth requirement and the usage hint are useful, but the redundancy costs points.

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?

There is no output schema, so the description carries the burden of describing the return value, and it does list the key fields (services, staff, price, client, notes). Combined with the auth note, this is nearly complete for a single-param read tool; only return format specifics are 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 description coverage is 100% and the single parameter is already documented in the schema ('Appointment ID from list_appointments'). The description adds no syntax or format detail beyond that, 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 one appointment') and enumerates the returned fields (services, staff, price, client, notes), which distinguishes it from booksy_list_appointments. It does not explicitly name the sibling it differs from, so it stops short of a 5.

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?

The sentence 'Use it before changing an appointment' implies a usage context (read-before-write), but no alternative tool is named and there is no statement of when NOT to use it or how it relates to booksy_reschedule_appointment or booksy_create_appointment. Usage is implied rather than specified.

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