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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, but the description adds genuinely non-obvious behavior: pending deliveries stop, the quota slot is released, and prior deliveries remain readable (i.e., history is not destroyed). That last point meaningfully qualifies the 'destructive' annotation.

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?

A single sentence, front-loaded with the action and followed by the three effects in priority order. No filler, no restatement of the title.

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, non-idempotency-sensitive tool with rich annotations and no output schema, the description covers the main behavioral questions an agent would have. Only minor gaps (e.g., behavior when watch_id is unknown/already cancelled) are unaddressed.

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?

Only one parameter (watch_id) and schema coverage is 100%, so the schema already documents it fully. The description adds no syntax, format, or sourcing detail beyond what the schema provides, so the baseline 3 applies.

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 (Cancels) and resource (a watch), and goes on to name the concrete consequences: no further deliveries, quota slot freed, earlier deliveries remain readable. This clearly separates it from watch_create, watch_list, watch_changes and watch_reevaluate.

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?

Usage is implied by the name and effect list, and the 'quota slot is freed' clause hints at one reason to invoke it, but there is no explicit when-to-use/when-not guidance or reference to the sibling watch tools an agent might confuse it with.

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