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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true), so the description's main added value is the '1 credit' cost disclosure, which is real operational context. It says nothing about failure modes for private/deleted videos, rate limits, or response shape.

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?

One sentence that leads with the resource and payload, then the input, then the cost. No filler and nothing redundant with structured fields.

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?

With no output schema, the description usefully enumerates what comes back (stats, caption, author, sound, download links) and states the cost, which is enough for an agent to call it. It could still note accepted URL shapes and what happens on invalid/private videos.

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% and the single required 'url' parameter has no schema description, so the description must carry it. 'by video URL' confirms the parameter is a full video URL rather than an ID or handle, but adds no format examples (e.g. vm.tiktok.com short links) or validation guidance.

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?

Names the exact resource (a TikTok video) and enumerates the payload fields returned: stats, caption, author, sound and download links, keyed by video URL. This distinguishes it from siblings like tiktokUser, tiktokComments and tiktokSearch, though it is phrased as a noun list rather than a verb+resource.

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?

'by video URL' implies the only invocation context: you must already have a video URL, so this is not a search/discovery tool. There is no explicit statement of when to pick it over tiktokSearch or tiktokUser, and no exclusions or prerequisites are given.

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