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

Annotations already mark it read-only and non-destructive, and the description adds meaningful behavioral detail: returned media URLs are temporary, eligible media is captured asynchronously into a managed dataset, region is fixed to US, and this is a metered live-data request. This is rich context beyond the annotations.

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?

Four concise sentences, each adding essential information. The core purpose is front-loaded, and the additional behavioral warnings are compact and no-words-wasted.

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 simple read-only fetch with one required parameter and an output schema present, the description covers URL acceptance, region behavior, temporary media URLs, async capture, and metering. Nothing critical is missing for an agent to invoke 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 0%, so the description must compensate. It does so by explaining accepted URL forms for the 'url' parameter and clarifying that content always resolves against the US region for the 'region' parameter. This adds real meaning beyond the bare schema.

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?

Description uses specific verb 'Fetch' with a clear resource ('TikTok video URL') and states exact outputs ('normalized details and current engagement metrics'). This clearly distinguishes it from siblings like get_tiktok_video_transcript and list_tiktok_video_comments.

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 gives useful usage context: canonical and share URLs are accepted, and the request resolves against the US region. However, it does not explicitly state when to prefer this over alternatives or when not to use it, leaving selection partly to inference.

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