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

Annotations already declare destructiveHint=true and idempotentHint=true, so safety is covered. The description adds genuine behavioral context beyond that: irreversibility ('Cannot be undone'), a quota cost ('50 quota units') for budgeting, and an ownership/auth requirement — none of which appear in the annotations or schema.

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 dense sentence front-loads the action and scope, then appends irreversibility, cost, and auth as short clauses. Every clause carries operational value 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 destructive two-parameter tool with no output schema, the description covers the key decision factors: what is destroyed, that it is permanent, quota cost, and permission requirements. It does not explain the return value or error behavior on a failed deletion, but nothing critical to invoking 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?

Schema description coverage is 100%, so both video_id and in_workspace are already self-documenting; baseline is 3. The description echoes the accepted 'youtube:video:<id>' format but adds no syntax or constraint detail beyond the schema, and says nothing about the in_workspace parameter.

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 ('Permanently delete') and resource ('a YouTube video by id'), with the permanent/irreversible scope made explicit. It is clearly distinguishable from siblings like youtube_update_video and youtube_upload_video without opening any schema.

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?

Provides useful preconditions ('Caller must own the channel') and warns of irreversibility, which helps the agent decide whether to proceed. However, it names no alternative (e.g., use youtube_update_video to privatize instead of deleting, or youtube_video_query to confirm the target first), so the when-vs-which guidance is only implied.

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