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

No annotations exist, so the description carries the full burden. It adds behavioral context by stating 'Cost = 1 token' and the either/or constraint, but does not mention read-only status, error conditions, or what happens if both parameters are provided. This is partially transparent but lacks depth.

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 three short sentences, front-loaded with purpose, then constraints, then cost. Every sentence provides value with no filler. It is concise and well-structured.

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?

The tool is simple with an output schema present, so return values are covered. The description covers the essential input constraint (either/or) and cost, which is sufficient for a metadata lookup tool. It lacks nothing critical, though it could mention potential errors or rate limits, but that is beyond the minimum for this complexity.

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% with descriptions for both video_id and video_url, so the baseline is 3. The description adds crucial semantics by explicitly stating 'not both,' which is not enforced by the schema. This goes beyond the schema's anyOf-null structure and clarifies the exclusivity requirement.

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 clearly states the tool's function with a specific verb ('Look up') and resource ('metadata for a TikTok video'). It distinguishes itself from sibling tools like tiktok.download_video and tiktok.video_comments by focusing on metadata retrieval.

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 explicit usage guidance: 'Provide either video_id or video_url, not both.' This clarifies the input constraint, but it does not mention when to choose this over alternatives (e.g., no other tool retrieves video metadata, so no alternative is needed). It gives clear context but no exclusions.

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