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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context: it returns pass/fail per rule and is free of charge, which matters because a caller might otherwise hesitate to validate repeatedly. It stops short of saying what happens on failure (does it block lunara_finish_upload?).

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 sentences, no waste. The rule list is front-loaded as the core purpose and the pricing note is a compact trailing clarification.

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 two-parameter read-only check with no output schema, the description tells the agent what it validates and what it returns at a granularity level. What's missing is downstream behavior on failure and any precondition on jobId (e.g., job must have finished segmenting/transcribing).

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 the schema fully documents jobId and the track enum. The description's 'both tracks' is consistent with the schema default but adds no format or selection guidance beyond it, which fits the baseline of 3.

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 (run the contract gate) and resource (subtitle tracks), and enumerates the exact rules checked: byte-exact ASR text/timings, cue length bounds, no empty cues. This clearly separates it from validation-adjacent siblings like lunara_readability and lunara_get_coverage.

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 phrase 'contract gate' implies it belongs before finalizing/delivering a track, and 'both tracks' hints at the default scope, but there is no explicit when-to-use guidance and no named alternatives such as lunara_readability or lunara_get_coverage. Usage is inferable but not stated.

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