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

With no annotations, the description carries the full burden. It usefully discloses the credit cost (video 3, audio 2) and that the result is a temporary link, but omits link expiry duration, rate limits, size/duration caps, and error behavior for unsupported URLs.

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?

Two tight sentences with the core action front-loaded and cost information appended. Nothing redundant or padded.

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 tool with no annotations and no output schema, the description covers the action and return type but leaves key operational details (link validity window, credit refund behavior on failure, capability limits) unspecified.

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 100%, so the schema already documents url, format, and quality with defaults and enum values. The credit line implicitly distinguishes video (mp4) from audio (mp3/m4a) formats, adding slight value, but overall the schema does the heavy lifting.

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 ('Download video from any URL') plus the return artifact ('temporary download link'). It clearly distinguishes itself from unrelated siblings like tts or transcribe, but does not name the closest sibling video-info, which the agent must infer is for metadata rather than downloading.

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?

There is no when-to-use guidance and no exclusions. The agent is not told to prefer video-info for metadata first, nor given prerequisites (e.g., supported platforms, whether a paid plan is required) that would route it correctly.

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