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

Adds a lot beyond the annotations (readOnlyHint=false, idempotentHint=false): the two-step ticket handshake, that the upload completes in-chat without Ads Manager or base64, that server-side fetch handles links Meta itself can't read, that the resulting video_id is reusable across ads, and the accepted formats/size cap. This is exactly the operational context an agent needs.

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 outcome ('Gets a video... returns its video_id'), then a tight numbered list keyed to user situations. Slightly long with a few filler phrases ('and that is all they do', 'carry on building the ad'), but nearly every sentence carries actionable information.

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?

Output schema exists so return values need not be described, and the description still supplies the full workflow, format/size constraints, and reusability note. Nothing an agent needs in order to select and execute this tool 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 description coverage is 0%, so the description must compensate, and it does: ticket is explained as the token returned by the drop-link call, and video_url is tied to case (2). account_id is never explained, which is the one gap, but the other two are covered well enough to invoke correctly.

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+resource ('Gets a video into the user's Meta ad account and returns its video_id'), names the return value, and explicitly distinguishes itself from the many sibling upload/create tools (upload_tiktok_video, upload_meta_image, create_meta_video_ad) by scoping to Meta video upload.

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 an explicit decision rule ('Three ways, pick by what the user has') and enumerates all three cases with their conditions: no argument + drop link flow, video_url for share links Meta cannot read, and reuse of an existing video_id. The when-to-use and when-not-to-use guidance is complete.

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