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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so 'read only' largely repeats structured data. The genuinely additive detail is 'Free' (no credit cost) and the '(links)' note about the return form, but there is no disclosure of empty-state behavior (what shows if nothing drawn yet) or ordering/limits.

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 short sentences, front-loaded with what is returned and followed by cost/safety framing. Slightly wasteful in that 'read only' duplicates the annotations, but there is no filler.

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 one-parameter, non-destructive read tool with no output schema, the description conveys the shape of the return (thumbnail ideas plus drawn images as links) and the cost profile. Only the empty-state and sibling relationship are missing.

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 videoId parameter already documents its own provenance (draft_video, list_my_videos, get_video). The description adds no further meaning about the parameter, so 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?

The description names a specific verb ('Shows') and a concrete resource: a long video's thumbnail ideas plus the pictures drawn so far, with links. It is clear what an agent gets back, but it never distinguishes this read tool from siblings like suggest_thumbnails or draw_thumbnails, so the boundary must be inferred.

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?

Usage is only implied: an agent can guess this is the way to inspect existing thumbnail ideas and drawings, presumably after suggest/draw steps. There is no explicit when-to-use, no named alternatives, and no prerequisites such as requiring a prior draft.

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