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

Annotations only supply destructiveHint=true; the description carries the real weight by disclosing the default refund/penalty/notification behavior, the effect of each flag, and the irreversibility of the operation. That is far beyond what the annotation provides.

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 scope limitation, then defaults, then flag semantics, then reversibility and endpoint. Every sentence adds a distinct operational fact with no filler.

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 still covers scope, defaults, flag semantics, reversibility, and the underlying endpoint. An agent has everything needed to call this destructive operation 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 the baseline is 3, but the description adds policy-level meaning: refund returns 'the member's payment or credit' and isLateCancellation applies 'the studio's late-cancel policy.' It does not explain disableNotifications, though the 'member IS notified' default implies it.

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 ('Cancel a SINGLE session booking') and immediately scopes out the sibling concept of a recurring series. An agent can distinguish the intent without opening the 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?

Explains the default behavior and when to set refund=true or isLateCancellation=true, and notes the action is not undoable except by re-booking. It stops short of naming an explicit alternative tool or an explicit when-not-to-use condition beyond the recurring-series scope.

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