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

Goes well beyond the annotations by disclosing that the result is saved as a new Studio version rather than mutating in place, that the operation is free (no credit cost), and that the new file is not produced until export_video runs. The annotations already signal a non-destructive write, so the remaining gap is minor: it doesn't say how long an edit takes or what happens if the instruction is ambiguous or unsupported.

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 action, then scope, then outcome, then exclusions — a sensible order with no filler sentences. The long parenthetical enumerations make it dense to parse in one pass, which keeps it just short of a 5.

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 mutation with no output schema, the description supplies everything needed: what can be edited, that the result is a new version, that export is required for a file, that it costs nothing, and where out-of-scope requests must be routed. Nothing an agent needs in order to call it or explain the result to a user is missing.

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% and both parameters are documented with examples, so the baseline is 3. The description does add some meaning by constraining what belongs in 'instruction' — a single plain-language request covering captions, music, cutting, text, speed or transitions — but it repeats rather than extends the schema's own example of user's-words phrasing.

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 ('Changes a made video in its ClipFlux Studio timeline') and immediately scopes it to one plain instruction, then enumerates the edit categories (captions, music, cutting, text, speed, transitions). It also names the sibling it is not (redo_scene) and the follow-up tool (export_video), so an agent can place it in the workflow without opening a schema.

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 when-to-use coverage by listing supported edit types, and explicit when-not-to-use: 'Anything that needs new pictures or new narration is not done here' with the correct alternative named (redo_scene) and the prerequisite (the user's yes). It also tells the agent that a new file requires a separate export_video call, closing the obvious next-step question.

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