video_visual_scan

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

With no annotations, the description carries the full burden and does well: it discloses that a lowest-quality video is downloaded (approx. 14-21MB for 7 minutes) and deleted afterwards, so the agent knows about cost and cleanup. It omits failure behavior (bad URL, inaccessible video) and does not describe the returned image's layout beyond "stitched."

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 tightly packed sentences: what it does first, then when to use it, then the cost caveat. No filler, and the critical constraint is front-loaded.

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 and no annotations, so the description must cover purpose, cost, and usage, which it does. What's missing is the meaning of cols/rows and any note on how the resulting image is laid out, which matters for interpreting the returned contact sheet.

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 0%, so the description must compensate. It explains n (number of frames) and the sampling rule, but cols and rows (the grid layout of the stitched image, defaults 6x4) are never mentioned anywhere, and url is only implied. Half the parameters remain opaque.

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: uniformly sample n frames across the video, burn absolute timecodes, stitch into an image and return it. It also indicates cut-point-aware sampling, which no sibling exposes. It does not distinguish itself from close siblings like video_frames or video_sheet, which also deal with visual frames, so a perfect score is not warranted.

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?

"Used for videos without sound, or long stretches without speech" gives a clear selection condition and implicitly steers audio-capable tasks to video_audio / video_soundscape / video_subs. However, it never names an alternative tool or states an explicit exclusion, so the agent must infer the routing.

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