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

Goes well beyond the destructiveHint/openWorldHint/idempotentHint annotations by disclosing recipient-level effects (unsent recipients become `unknown`, sent ones retain status), the exact error contract (422 with `reason: already_finished`), draft handling, and the admin + feature-flag auth requirements. This is exactly the extra behavioral context annotations cannot carry.

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?

Front-loaded with the action and its permanence, then recipient effects, error behavior, draft scope, and permissions in descending order of importance. Every sentence carries distinct operational information with no filler.

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 tool with no output schema, the description covers success semantics, side effects on recipients, the failure case, and authorization requirements. Nothing an agent needs to call it correctly is missing.

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?

Single `id` integer parameter at 100% schema description coverage, so the schema already documents it fully. The description adds no format or sourcing detail beyond what the schema states, making the baseline 3 appropriate.

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?

Specific verb+resource ("Cancel a campaign") followed by a scope statement ("Ends the campaign for good") that implicitly separates it from pause/delete siblings. It never names an alternative tool, so an agent must still infer the boundary from the 'for good' phrasing.

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 clear preconditions: admins only, `whatsapp_campaigns` feature required, drafts are cancellable, and finished/failed campaigns are rejected with 422 `already_finished`. It stops short of explicitly contrasting pause_whatsapp_campaign or delete_whatsapp_campaign as the alternatives for non-terminal outcomes.

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