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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered; the description earns credit for disclosing the $0.006-per-request billing cost, which is not in any structured field. It stops short of rate limits or auth requirements.

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 sentences, front-loaded with the identification method, then return contents, then cost. No filler or repetition of the title.

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?

No output schema exists, so enumerating the returned fields (counts, watermark-free playback/download URLs, cover images, music, author) is necessary and present; the billing note rounds out what an agent needs for cost-aware selection.

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 baseline is 3; the description adds the mutual-exclusion rule ('provide exactly one') that the schema itself cannot express since both properties are optional. That is real semantic value beyond the field descriptions.

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 ('Get one TikTok video') and the two accepted identifiers, which cleanly separates it from tiktok_user_profile (users) and search_tiktok (discovery). The description also previews the returned payload, so an agent knows exactly what it gets before opening anything else.

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?

The 'provide exactly one' clause is an actionable input constraint, but there is no explicit when-to-use/when-not guidance and no sibling is named as an alternative (e.g., search_tiktok to find a URL first) the way the calibration HIGH example does.

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