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

Annotations already flag destructiveHint=true and readOnlyHint=false, so the bar is lower; the description still adds real context by specifying that stored files are removed, that active-run lists are skipped, and that the operation is free. It stops short of stating irreversibility or any permission/scope requirement beyond 'this workspace'.

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 data consequence, then mode behavior, then the skip rule. Nothing is padding and no sentence restates the title.

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 one-parameter destructive tool with no output schema and strong annotations, this covers impact, selectivity, and cost. The only notable gap is that 'idle' is never defined, which the agent needs to predict what will actually be purged.

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% and the enum's own description already spells out 'all (default)' versus 'temporary non-Forever lists', so the description largely repeats structured content. It does contribute the framing of 'idle' as the selection criterion, which is not encoded in 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?

The description names a specific verb and resource ('Purge idle Hosted Lists') and adds the material consequence that their stored files are deleted. It does not explicitly distinguish itself from the sibling delete_list, so an agent must infer whether this is a bulk alternative to that single-list delete.

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?

Usage context is concrete: idle lists only, lists with active runs are skipped, and the two modes are conditioned ('temporary' for non-Forever, 'all' as default). No exclusion or comparison against delete_list is given, so the when-not guidance is only partial.

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