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

Beyond the annotations (which only say non-read-only, non-destructive, closed-world), the description discloses the cost (~0.4 credit, reported in the result), what the output contains, that chapter times are real for long videos, and that tags are NOT applied by posting. That is exactly the extra behavioral context the annotations cannot carry.

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 compact sentences, front-loaded with what is produced, then cost, then the invocation condition and downstream handoff. No filler; each sentence carries operational information.

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?

Covers output shape, cost, downstream usage, and a real limitation about tags, which is thorough for a one-parameter generation tool. It does not say what happens if the video lacks a script or how long generation takes, a minor remaining gap with no output schema.

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% and the single videoId parameter already documents its source tools (draft_video, list_my_videos, get_video). The description adds no additional meaning about the parameter, so the baseline 3 applies.

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?

"Writes 10 title options, a description and tags for one of the user's videos from its own script" names a specific verb, the exact artifacts produced (including counts), and the source material. It is clearly distinguishable from siblings like draw_thumbnails or post_video.

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?

It states explicit trigger conditions ("when the user asks for titles, a description or tags, or for the upload text") and gives the follow-on workflow: show titles, let the user pick, then pass the chosen title and description to post_video. Exclusions are implicit but the routing is unambiguous.

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