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

Annotations already declare it safe, read-only, and idempotent, so the bar is lower. The description still adds real value beyond them: it discloses the not-found behavior ('Media not found') and a safety caveat to treat the returned user-generated content as untrusted input.

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?

Front-loaded with purpose and usage before the return-field list, with no wasted preamble. The field enumeration is somewhat long but justified because no output schema exists.

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 simple one-parameter lookup with annotations covering the safety profile and no output schema, the description supplies everything needed: purpose, usage context, enumerated return fields, the not-found case, and the untrusted-content warning.

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 the single parameter is fully documented, so the baseline is 3. The description's 'by its ID (pk)' merely echoes the schema's 'TikTok video ID (pk)' and adds no syntax or format detail beyond it.

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 and resource — 'Get one TikTok video by its ID (pk)' — and clarifies the identifier type. It is clear what the tool retrieves, but it does not explicitly distinguish itself from siblings like get_media_by_code or search_tt_media_captions, leaving differentiation to inference.

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 it for full details of a video from list results' gives concrete context for when to reach for this tool. However, it names no exclusion or alternative (e.g., when to prefer get_media_by_code instead), so guidance is clear but incomplete.

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