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

Annotations already indicate destructive Hint=true and readOnlyHint=false. The description adds the non-obvious boundary that only scheduled messages are cancelable, which is material behavior not present in structured fields. It does not contradict the annotations.

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?

The description is one concise, front-loaded sentence with no filler. The core action and the critical constraint are both included without redundant wording.

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 one-parameter destructive tool, the description covers the essential context: scheduled emails can be canceled, sent ones cannot. There is no output schema, and the example-like omission is minor; it does not need to explain return values.

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?

With 0% schema description coverage and no parameter documentation, the description provides little direct meaning for the `id` parameter. It is implicitly the identifier of the scheduled notification, but the description never explicitly states that the parameter represents the notification to cancel.

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?

The description states a specific action ('cancel') on a specific resource ('scheduled notification email'), and the follow-up clause clarifies that sent messages are out of scope. This distinguishes it from general deletion tools like hires_delete_message and from batch cancellation like hires_cancel_all_notification_messages.

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 clearly identifies the target case (scheduled notification emails) and an explicit exclusion (sent messages cannot be canceled). Though it does not name alternative sibling tools, the when-to-use condition is explicit enough for an agent to select it correctly.

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