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

Adds information beyond the annotations: the exact price model ($0.02/1,000 words, $0.01 minimum) and the fact that existing or same-language results cost nothing, which is consistent with idempotentHint=true. It does not explain why destructiveHint=true applies to a translation request, which is the one behavioral gap an agent might trip on.

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 tight, front-loaded sentences: the action first, then the cost model. The pricing clause is slightly dense but every element (cost, minimum, zero-cost cases) is decision-relevant rather than 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?

There is no output schema, so the description should at least hint at what happens after the request (async job, how to retrieve results via get_call_translations) and what 'eligible' means; it covers cost but leaves outcome and eligibility undefined. Annotation-covered safety plus the cost detail keeps this at minimum-viable rather than inadequate.

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 0% and both parameters (call_id, target_language) are undocumented in the schema, yet the description never clarifies identifier format, acceptable language codes, or what makes a call 'eligible.' The phrase 'per target' is the only hint about target_language and it is not enough to compensate for the coverage gap.

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?

Names a specific verb and resource ('request paid stored-text translation for an eligible new call') and makes the call-vs-message scope implicitly clear against siblings like request_message_translation and get_call_translations. It does not explicitly name an alternative, but the action is unambiguous.

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?

Gives a real usage condition: this is the explicit path to use 'even with automatic translation off,' and noting that existing ready results and matching-language text cost zero tells the agent there is no need to call when results already exist. No explicit exclusions or named alternative tools, but the context is clear.

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