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

Beyond the annotations (readOnlyHint, openWorldHint, destructiveHint), the description discloses important behaviors: returned media URLs are temporary, media capture is asynchronous, content resolves against the US region, and the request is metered. These details meaningfully inform an agent's expectations and would not be inferred from the schema or annotations alone.

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?

The description is compact yet information-dense. The main action is front-loaded in the first sentence, and each subsequent sentence adds a specific caveat or behavioral detail. No filler or redundant phrases are present.

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?

Given the tool's simplicity (one required parameter, fixed region, output schema provided), the description covers all essential call-time context: URL format variants, region behavior, temporary media URLs, asynchronous capture, and metering. An agent has enough information to correctly select and invoke the tool without encountering surprises.

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 0%, so the description must compensate for parameter meaning. It does so by explaining what URL forms are accepted ('Canonical video URLs and TikTok share URLs') and clarifying that the region is always US ('Content always resolves against the US region'). This adds practical semantics beyond the bare 'uri' format and 'const: US' in the schema.

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?

The description opens with a specific verb ('Fetch'), a clear resource ('TikTok video URL'), and the exact kind of data returned ('normalized details and current engagement metrics'). This clearly distinguishes it from sibling tools like get_tiktok_profile, get_tiktok_video_transcript, and list_tiktok_video_comments, which concern different resource aspects.

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 description provides clear context for when to use the tool: it accepts canonical and share URLs and is a metered live-data request, implying it should be used when current engagement metrics and normalized details are needed. It does not explicitly name alternatives or exclusions, but the accepted URL types and live-data warning offer actionable usage guidance.

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