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

Annotations cover the safety profile (readOnlyHint=true, openWorldHint=false), and the description adds substantial context beyond them: the data provenance (measurement of 349 videos), the rate spread (160/181/201 wpm), and the scope caveat that pauses and B-roll are excluded so real edits run longer. That is exactly the kind of expectation-setting an agent needs before quoting a number to a user.

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?

Front-loaded with the core operation, then usage triggers, then the caveat — a sensible order. The percentile figures are slightly dense but they justify the rate model rather than padding, so 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?

With no output schema, the description does the work of saying what comes back (a runtime range, or a word budget). Combined with the 100%-covered parameter schema, an agent has enough to invoke correctly; only minor detail like exact rounding or whether multiple inputs may be combined is left implicit.

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 baseline is 3, but the description goes further by explaining the three distinct input modes and what each produces (word count → range, pasted script → range, target minutes → word budget). It doesn't restate the mutual-exclusivity rule, which the schema already handles.

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 bidirectional operation: word count/script → runtime range, and target runtime → word budget. An agent can tell exactly what it does without opening the schema, and the purpose is distinct from the audit-oriented siblings.

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 explicit trigger phrasings ("how long will this script run", "how many words for a ten-minute video") and an explicit exclusion (pauses, B-roll, demonstrations), which tells the agent when the answer will understate a finished edit. No sibling alternative is named, but none of the siblings is a substitute for this arithmetic tool.

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