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

Annotations only supply destructiveHint=true; the description carries the real behavioral payload, disclosing the three defaults (no refund, no late-cancel penalty, member notified) and the irreversibility ('Not undoable except by re-booking'). These are exactly the consequence-level details an agent needs before a destructive call.

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 scope, then defaults, then the two opt-in flags, then irreversibility. Every clause is decision-relevant; the trailing API-endpoint note is the only near-filler and is short.

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 tool with minimal annotations, the description covers scope, defaults, opt-in side effects, notification behavior, and reversibility. Nothing an agent needs to invoke 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, but the description adds consequence meaning the schema lacks: refund=true returns payment or credit, isLateCancellation applies the studio policy, and 'the member IS notified' implicitly explains disableNotifications. Modest but genuine value beyond the field docs.

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 ('Cancel a SINGLE session booking') and immediately disambiguates scope by excluding recurring series. An agent can distinguish this from booking/list siblings and from any series-cancellation tool without opening a 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 explicit conditions for the two optional toggles: 'Set refund=true only to return the member's payment' and 'isLateCancellation=true applies the studio's late-cancel policy', plus the exclusion of recurring series. It stops short of naming the sibling tool to use for a recurring series, so routing is implied rather than fully closed.

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