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

Annotations only cover safety (not read-only, not destructive, closed-world); the description adds crucial domain behavior: an uploaded video only surfaces via a `custom-footage` moment and 'uploading it alone does nothing', plus that footage plays muted. It doesn't discuss reversibility or auth beyond what annotations imply, but the non-obvious side effects are disclosed.

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-loads the key caveat ('Optional — except for uploaded videos') and packs type definitions and examples efficiently. It is dense but nearly every clause carries needed information; only the type enumeration could be tightened.

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 six-parameter tool with a nested object and an enum, and no output schema, the description covers when to use, all type semantics, the footage constraint, tagging, and script-length ordering. An agent has everything needed to call it correctly.

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 high (83%), so the baseline is 3, but the description earns more by explaining what each type means (product-shot vs faceless, b-roll, product-action, talking-person), the `footage` requirement and muted playback, and the @[Name] tagging syntax with a concrete example.

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 ('Adds a required moment: a scene the ad must contain') and immediately explains the mechanism (script written around it, storyboard places it). It is clearly distinguishable from sibling add_subject and remove_moment.

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?

Explicitly frames it as 'Optional — except for uploaded videos', states the null case ('without moments the script and storyboard decide everything, which is fine'), and gives ordering ('Add moments before generate_script; the total must fit the script's length'). This is textbook when/when-not guidance.

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