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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered. The description adds real value beyond that: irreversibility, the pre-start-time window, the server-side error behavior, and the underlying REST shape (POST /api/campaign with Action delete). It does not describe the confirmation workflow or recipient-side consequences, which keeps it from a 5.

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, mutation intent front-loaded, then the timing constraint, then the irreversibility warning. Every sentence carries distinct information with no restatement of the title or schema.

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 only two fully documented parameters and no output schema, the description covers the essential calling context: what is destroyed, when it is allowed, and why failure occurs. Minor gap is the absence of any mention of the confirmation requirement that gates the write, which the schema carries alone.

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 description coverage is 100%, so both parameters, including the confirm gate with its user-confirmation guidance, are fully documented in the schema. The description adds no parameter-specific detail such as where the campaign_id comes from or when confirm should be set, 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 and resource ("deletes a scheduled SMS campaign so it is not sent") and makes the effect on delivery explicit. It does not name the closest sibling, pause_campaign, though the "cannot be undone" phrasing implicitly separates it from a reversible pause.

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 and when-not: only works before the campaign start time, after which the API refuses with an error. It lacks an explicit pointer to pause_campaign as the alternative for campaigns already running, so routing to the right sibling is left partly to inference.

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