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

Beyond the destructive/open-world annotations, it discloses a non-obvious batch behavior: for Facebook and Instagram, all requested videos must be READY or the entire batch is refused and nothing is created. It does not explain what an update overwrites, but the annotations already signal destructive mutation.

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?

Three compact sentences front-load the tool identity, the create/update switch, and the critical Facebook/Instagram readiness failure mode. There is no filler.

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 complex nested ad payload, the description covers the key operational distinctions and a major failure condition while leaving field-level requirements to the fully documented schema. It does not describe return values, but no output schema exists and the core calling behavior is sufficiently clear.

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 detailed nested fields, enums, per-channel requirements, and creativeID meaning are already documented in the schema. The description adds the create-vs-update meaning of `id`, but that is also stated in the schema, so it does little beyond the structured fields.

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 states a specific verb and resource: create or update a VIDEO ad on named channels. The 'VIDEO' qualifier distinguishes it from sibling ad-creation tools such as create_update_image_ad and create_update_carousel_ad.

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?

It clearly explains how to select update versus create behavior by including or omitting `id`, and it states an important prerequisite for Facebook/Instagram readiness. It does not explicitly route agents to related tools like upload_video_creative or name alternatives for other ad formats.

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