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

Annotations already declare destructiveHint=trueabb. The description adds that it targets scheduled messages and must occur before sending, providing useful behavior context. No details on idempotency or error behaviors beyond the annotation safety profile.

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?

One clear sentence, front-loaded with the verb and subject. No filler or redundant restatement of the tool name.

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 simple single-parameter destructive operation, the description plus annotations are mostly sufficient. The 'before it is sent' constraint clarifies the primary edge case that gates the operation. Missing details about failure when the message is already sent, but the phrasing implies the limitation.

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 has one parameter (`id: integer`) with zero description coverage (0%). The description never mentions the parameter, so an agent must infer that `id` refers to the scheduled message ID. Minimal compensation for the schema gap.

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?

Description states a specific verb ('Cancel') and resource ('a scheduled message'), distinguishing it from sibling delete tools like hires_delete_notification_message. The qualifier 'before it is sent' adds scope.

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 description implies when to use (only for scheduled messages that haven't been sent), but it doesn't explicitly contrast it with alternatives like hires_delete_message vs hires_delete_notification_message. It provides context but no explicit exclusion or alternative routing.

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