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

Annotations only declare readOnlyHint=false, so the description carries most of the burden and does add real value: it discloses the calendar write, auto-generated Google Meet/Teams link, ICS invite emails to guests and host, and the auth/human-bot-check requirement. However, it omits failure modes, whether a confirmed slot is atomic/locked, and rate limits, so it stops short of a full behavioral picture.

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 purpose and the critical startsAt constraint in the first two sentences, then covers side effects and return values. Dense but slightly redundant with the schema on defaults and the startsAt source, which keeps it short of 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?

With no output schema, the description compensates by naming the return fields (bookingId, conferenceUrl, meetingUrl, manageUrl) and their cancel/reschedule purpose. Combined with side effects and auth requirements, an agent has everything needed to call this correctly.

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 every parameter already has a documented meaning and defaults. The description mostly restates schema content (startsAt source, name/email defaults) rather than adding new syntax or constraint meaning, which lands at the baseline for full-coverage schemas.

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 ('Book a time on someone's WhenMeet.me booking link') and immediately names the sibling it depends on (get_booking_slots). It does not explicitly distinguish itself from create_meeting, the other scheduling-write sibling, so sibling differentiation is only partial.

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 a hard prerequisite ('startsAt must be a slot start from get_booking_slots') and a clear alternate-case rule for name/email ('pass them to book for someone else'). It also states an authentication requirement and the bot-check exception, though it never states when NOT to use this tool vs create_meeting.

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