Detect Active Picture Bounds

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

Annotations give a partial safety profile (destructiveHint=false, openWorldHint=false), and the description adds that decoding samples occur and that the source is left untouched. It still does not explain why readOnlyHint=false for a purely analytical probe, nor any cost/time implications of decoding.

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?

A single front-loaded sentence that names the operation, the artifact detected, and the non-destructive guarantee with zero 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?

With an output schema present, return values need not be described, and all three parameters are documented in the schema. Adequate for this read-oriented probe, though the absence of guidance on when to reach for it versus crop_clip or scope-reading tools leaves a small gap.

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% (limit, media_path, sample_seconds all documented inline), so the schema carries the parameter burden. The description adds no format, default, or constraint detail beyond it — baseline 3.

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 ('detect') plus a precise resource ('the most frequent active-picture crop rectangle ... probable letterbox or pillarbox bars'). This clearly separates it from mutation siblings such as crop_clip by stating it only measures, not changes, the material.

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 implied rather than stated: the letterbox/pillarbox framing and 'without modifying the source' hint it is a diagnostic step preceding a crop. There is no explicit when-to-use, when-not, or named alternative (e.g., read_video_scopes, crop_clip).

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