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

Annotations already declare write, destructive, non-idempotent, so safety is covered. The description adds the genuinely useful operational constraint of a 100-number batch ceiling and clarifies the compliance meaning (do-not-call list), which the annotations cannot convey. It stops short of saying what happens on duplicates or whether re-adding an existing optout errors, given idempotentHint=false.

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 short sentences, zero padding, with the write marker and the batch limit front-loaded before the parameter hint. Every clause carries information.

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, non-idempotent write with no output schema and zero schema coverage, the definition covers purpose, the batch cap and one parameter. Missing are duplicate/already-opted-out behavior, number formatting requirements, and what the call returns, which matter for a suppression-list mutation.

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?

With 0% schema description coverage the description must carry all parameter meaning, and it only explains voip_optout_country (calling code that completes numbers starting with 0), implicitly hinting at number format. The required voip_optout_numbers format (national vs E.164, separators) and voip_optout_note are left undocumented anywhere.

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 and resource: putting numbers on the do-not-call list. The compliance effect is explicit, so an agent knows the outcome is a suppression list entry, not, say, a campaign target import. It does not name its natural sibling (list_voip_optouts) for verification, keeping it below a 5.

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 '[write]' tag and the 'at most 100 per call' cap imply the context of use, but there is no explicit statement of when to prefer this over import_voip_campaign_targets or when to check list_voip_optouts first. No exclusion or prerequisite guidance is given.

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