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

Annotations already mark destructiveHint=true, so the description adds marginal value by stating the operation is destructive and requires explicit confirmation. The 'Side effects: deletes fax record' line only restates the main action and adds no new behavioral detail beyond the annotation.

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?

The description is short and front-loaded with the core action, which is good. However, the second sentence 'Side effects: deletes fax record' is redundant with the first sentence and does not earn its place, making the structure slightly wasteful.

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 delete operation with full schema coverage, an output schema, and destructiveHint annotation, the description covers the essential behavioral caveat: explicit confirmation is required. It is complete enough to invoke correctly, though it would benefit from naming the outbox variant as the alternative for outbox faxes.

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?

Input schema coverage is 100%, so the baseline is 3. The description's mention of 'explicit confirmation' gives slight context for the confirmation_text parameter, but it does not explain fax_id, user_id, or the exact confirmation semantics beyond what the schema already states.

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 clear verb and resource: 'Delete a fax record.' It is not a tautology, but it does not explicitly differentiate from the sibling tool delete-outbox-fax, so the agent must infer the distinction from the tool name rather than the description.

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?

The description gives no guidance on when to use this tool versus alternatives such as delete-outbox-fax or update-fax. The warning that the operation is destructive and requires explicit confirmation is safety guidance, not usage context.

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