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

Annotations declare idempotentHint=true and destructiveHint=false but leave readOnlyHint=false unexplained for a tool that mainly renders a preview image; the description fills this gap by stating it renders layers the timeline lacks and is free (no credits). It also adds valuable failure behavior: a second past the end errors with the film's length rather than silently clipping.

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 the core purpose, then prerequisites, sibling contrast, parameters and cost. Dense and mostly earning its place, though the quoted example questions and layered parentheticals push it slightly past what an agent needs.

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 must cover what comes back — it does ('tiled into one image and shown', inline via preview), and it covers scope limits (max 12 frames), cost, prerequisites and error behavior. Nothing needed to call it correctly is 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 coverage is 100%, so baseline is 3; the description still adds semantics beyond the schema, notably the mutual exclusivity of `sekunden` vs `verteilt` and the default of 6 frames when both are omitted, plus the failure mode for out-of-range seconds.

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?

Specific verb and resource: 'See the DELIVERED film: up to 12 frames from the finished export ... tiled into one image and shown.' It names the exact pipeline stage (lab_start_export → lab_get_export status done) and explicitly differentiates itself from the closest sibling lab_capture by contrasting pre-render cut vs delivered render.

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?

Explicit when-to-use with a concrete example ('is the lower third readable at 7 s, does the badge cover anything'), an explicit when-NOT-to-use route to lab_capture, prerequisites (finished export with video, not archive/PNG-sequence profiles), and the free/no-credit cost note.

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