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

Adds real context beyond the annotations: every cue boundary and timestamp is preserved, only text changes, which tells the agent exactly what the mutation touches. It does not say whether the translated text replaces the source track or is written to a new track, a meaningful gap for a readOnlyHint=false operation.

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 with zero padding, front-loading the action and then the guarantee that matters. Nothing repeated from the schema or annotations.

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 3-parameter mutation tool with full schema coverage and annotations, the description covers purpose, timing guarantee, and the reason to prefer it over manual translation. The remaining ambiguity about output (new track vs in-place) and return value is the only real shortfall, and no output schema exists to cover it.

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 coverage is 100%, so jobId, track, and targetLang are all documented with enums for the latter two. The description reinforces that jobId refers to an existing job but adds no new semantics about the track parameter or language options; baseline 3 applies.

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: translating the cue text of an existing job into another language, plus a precise scope note that only text changes. It does not explicitly differentiate itself from sibling lunara_rewrite, which also mutates cue text, so the agent must infer the distinction from 'into another language'.

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?

'Use this instead of translating yourself so the timing contract holds' gives a clear selection rule against the main alternative (agent-side translation). It stops short of naming sibling tools or stating when-not to use it (e.g., when a rewrite rather than a translation is wanted).

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