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

The destructiveHint annotation is true, and the description meaningfully expands on it by stating exactly what gets destroyed (files) and what happens to the preview's URL. It also adds the 24-hour auto-expiry behavior, which is not available from annotations alone.

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?

Two sentences with no filler. The core action and effects are front-loaded, followed by necessary context about expiration and use cases. Every sentence earns its place.

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 simple one-parameter destructive tool, the description is complete: it explains the action, consequences, when to use it, and the automatic expiration behavior. No output schema is needed for this operation, and nothing essential 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?

Schema coverage is 100%, with previewId documented as 'Preview id from publish_preview or list_sites'. The description adds no extra parameter-level detail, so the baseline of 3 is appropriate since the schema already carries the full burden.

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 ('Discard a preview immediately') and its concrete effects: the URL stops serving and files are deleted. This clearly distinguishes it from siblings like update_preview or publish_preview, which modify or create rather than destroy.

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?

It explicitly says when the tool is needed ('only needed to free a cap slot early or retire a shared link') and when it is not ('Previews also expire on their own after 24 hours'). This gives the agent clear selection criteria, including the alternative of simply letting the preview expire.

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