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

With no annotations, the description carries the disclosure burden and does well: it reveals the side effect (only the first frame is persisted), the omission of other artifacts, and the cost (0 credits). It does not state whether it writes to the database, auth requirements, or rate limits, but the cost and storage semantics are the operationally important traits here.

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 short sentences, each carrying distinct information: purpose, storage constraint, cost, and usage trigger. The primary action is front-loaded and 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 single-parameter scrape tool with no output schema and no annotations, the description covers what it produces, what it does not produce, cost, and when to call it. Return shape details (metadata fields) are unspecified, which is the only meaningful gap.

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?

There is a single parameter at 100% schema coverage; the schema already documents the url field and supported platforms (TikTok, Instagram, YouTube). The description adds no format or validation detail beyond what the schema states, so a baseline 3 is appropriate.

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 (Scrape) and resource (a video URL) and names exactly what is produced: the first frame plus metadata. This is easily distinguished from sibling generators like generate_video or stitch_video, which create rather than extract.

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 concrete triggering conditions: a database result lacking cleanThumbnailUrl, or a user-supplied new URL. It also bounds behavior with 'No video clips or extra frames saved.' It does not name an alternative tool for the case where a full clip is actually needed, which is the only gap.

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