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

With no annotations, the description carries the full burden and does well: it discloses the one-page limit, the volatility between calls, the 3-credit cost regardless of cache, and the refund on failed calls. It stops short of stating auth requirements or rate limits.

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 front-loaded with a distinct fact: purpose, pagination/volatility, use case, and cost. No filler; every sentence earns its place.

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 no-annotation, no-output-schema tool, it covers pagination, result volatility, and cost/refund, and 'each a full video' hints at the return shape. Only auth/permission requirements are left unaddressed.

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 description coverage is 100% and both parameters (fresh, region) are fully documented in the schema, so the baseline is 3. The description's mention of caching loosely relates to 'fresh' but adds no syntax or semantics beyond what the schema already states.

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 (Fetch), resource (trending feed videos), and scope (one country, now), plus the differentiating trait 'each a full video'. This clearly separates it from siblings like get_tiktok_videos and search_tiktok, which are ordinary lookups rather than the trending feed.

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?

'Use this to see what is spreading' gives a clear intended context for selection, and the note that results change call to call implicitly warns against treating it as a stable list. However, no explicit when-not guidance or named alternative (e.g. get_tiktok_videos for a specific account's uploads) is provided.

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