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

Annotations declare destructiveHint=true, and the description builds on that with real substance: a required staff user token, a validate-only mode, the fact that cancel is withheld because of a client charge, and a hard statement that only certain fields are mutable. This is the kind of context annotations cannot carry.

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-loaded with the primary action and reason for the cancel exclusion; the parenthetical enumerations are efficient. The trailing 'Mindbody: POST /appointment/updateappointment' line adds little for an agent choosing or invoking the tool.

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?

For a destructive, no-output-schema mutation tool this covers the essentials: what changes, what is forbidden, the required auth context, a dry-run escape hatch, and the underlying endpoint for error mapping. Nothing an agent needs to call it safely is 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 coverage is 100%, so the baseline is 3; the description still adds meaning by asserting that start/end time, staff, session type and notes are the only fields Mindbody permits changing, which constrains expectations for the full 9-parameter surface (send_email, execute, test are left to the schema).

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+resource combination ('Reschedule or edit an appointment') and enumerates the two distinct mutation axes: field edits (time, staff, session type, notes) and status transitions (confirm/unconfirm/arrive/unarrive/complete). It is clearly separable from the add/list siblings at a glance.

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?

Explicitly frames when to use it (reschedule/edit and/or status change) and when not to (cancel and late-cancel are deliberately excluded, with the reason: a late cancel can charge the client). Adds a dry-run path via test:true, which routes the agent away from unintended writes.

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