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

Annotations declare destructiveHint=true and idempotentHint=true with readOnlyHint=false; the description adds the precondition failure mode (an ended job can't be cancelled). It doesn't restate idempotency, which annotations already cover. The auth disclosure ('No API key...call it directly') is useful additional context.

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?

Three short sentences, front-loaded with the action and its precondition. The auth sentence is somewhat tangential but brief.

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 single-parameter destructive mutation with annotations covering safety, the description supplies the key missing behavioral fact (cannot cancel a finished job). It could note what cancellation does to the schedule record, but is largely complete.

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?

One required parameter with 0% schema description coverage. The description does not explain schedule_id's format, even though the schema pattern defines a UUID. Baseline 3 for a single-param tool where the name is self-explanatory, but the description adds no meaning beyond the schema.

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 (cancel) and resource (scheduled webhook), and adds a scope qualifier ('that has not finished'). Clearly distinguishes this from sibling schedule_webhook and read_webhook_schedule.

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 a clear precondition for when the tool can be used ('has not finished') and what happens otherwise ('A job that has already ended cannot be cancelled'). No sibling alternatives are named, but the when-to-use condition is explicit.

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