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

Goes beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false) by disclosing that timing is estimated by the local renderer and that the call is billed by input characters, which is valuable pre-call context. It does not cover failure behavior or whether output timing is approximate per-line, but the operational disclosure is solid.

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, no filler, with the core behavior (translate, preserve count/order) front-loaded and secondary details (timing estimate, billing) following. Every sentence earns its place.

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 must convey return behavior; it states count/order preservation and estimated timing, which helps. However, for a non-idempotent, billable, open-world tool with a 4-param schema at 25% coverage, the undocumented glossary and unsettled target_language format leave meaningful gaps.

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 only 25% (only request_id is documented), so the description carries the burden. It adds value for the captions parameter (count/order preserved) and ties billing to input characters, but the glossary parameter is left completely undocumented in both schema and description, and target_language format is unspecified.

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+resource ('Translate caption lines') with the scope constraint that count and order are preserved. It is clearly a translation operation, though it does not distinguish itself from siblings like correct_captions or explain why one would translate here rather than elsewhere.

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 is implied rather than stated — you use it to translate captions — and the mention of billing by input characters hints at cost-related siblings (estimate_cost, get_pricing) without naming them. No explicit when-to-use or when-not-to-use guidance is given.

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