extract_video

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

With no annotations, the description carries the full burden and does it well: it discloses that files are written to disk, HD selection when exposed, magic-byte verification of downloads, and the no-auth requirement. It does not cover overwrite behavior for an existing out_dir, rate limits, or failure modes beyond noting an errors field in the returned envelope.

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?

Two sentences, front-loaded with the action and resource, followed by the return payload. Parenthetical qualifiers ('HD when exposed', 'all magic-byte verified') earn their space, though the second sentence packs a long field list that borders on dense.

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?

No output schema exists, so the description compensates by enumerating the manifest envelope contents (author, title, stats, music identity, media URLs, local files, errors, decode-slot provenance), and it covers the auth precondition. Only minor gaps remain, such as out_dir overwrite behavior and any rate-limit expectations.

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%, so the schema already documents url, out_dir, and download_media, making 3 the baseline. The description adds mild value by restating accepted URL forms and clarifying that the video, soundtrack and covers all land in out_dir, but it introduces no syntax or format detail the schema lacks.

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 a specific verb (Harvest) and resource (public TikTok video), enumerates what is fetched (video in HD, soundtrack, covers) and what is returned. It implicitly contrasts with lookup_video by emphasizing downloading rather than just metadata, but never names a sibling explicitly, so differentiation is left 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?

The description gives a precondition ('given a video/photo URL, short link or bare video id') and a note that no login or API keys are needed, but offers no when-to-use/when-not guidance and never mentions lookup_video or read_manifest as alternatives. An agent choosing between harvesting, looking up, and reading a manifest gets no routing help.

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