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

With no annotations, the description carries the full burden. It clearly indicates a non-destructive audit (no modification verbs), lists the types of cues that get flagged, and states that a formatted report is returned. It goes beyond the schema by describing the output format and the nature of the checks. It does not disclose edge cases or limitations, but for a read-only audit tool the disclosed behavior is sufficient.

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?

The description is a single, tightly structured sentence that front-loads the purpose ('audit subtitle readability') and then lists the criteria and output. Every clause adds information without redundancy. It is both concise and information-dense.

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?

Given no output schema, the description appropriately explains the return value ('formatted report listing every flagged cue'). It covers the tool's purpose, checks, and output. Minor gaps remain (e.g., input format expectations, error handling), but for an audit tool with fully documented parameters, the description is complete enough for correct invocation.

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 100%, so the schema already documents all five parameters. The description adds little beyond connecting parameters like max_cps and max_line_length to the checks they influence, but this is supplemental rather than necessary. Baseline 3 is appropriate since the schema does the heavy lifting.

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?

The description opens with a specific verb 'audit' and the resource 'subtitle readability', immediately distinguishing this from sibling transformation tools. It enumerates the exact checks (CPS, durations, line width, line count, overlaps) and states the output is a formatted report. This makes the tool's purpose unambiguous and clearly differentiates it from tools like clean_subtitles or merge_subtitles.

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 description implies this is the tool to use when you need to verify subtitle quality, but it does not explicitly state when to use it vs alternatives or when not to use it. While the audit nature makes it obvious it is not for editing, there is no explicit exclusion or mention of a fallback tool. Guidance is present implicitly but not spelled out.

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