Detect Active Picture Bounds

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

The description adds meaningful behavioral context beyond the annotations: it clarifies that the source is not modified despite readOnlyHint=false, and it reveals that detection is based on the most frequent crop rectangle in decoded video. This helps set expectations about the heuristic nature of the result.

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, well-structured sentence front-loads the action and outcome while including the key safety caveat. Every phrase earns its place; there is no redundancy or 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 and all parameters documented in the input schema, the description covers the essential purpose and side-effect caveat. Slight incompleteness remains in the absence of usage-vs-alternative guidance, but nothing needed to invoke the tool 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 description coverage is 100%, so the schema already documents limit, media_path, and sample_seconds. The description adds no parameter-level semantics beyond what the schema provides, which is acceptable but not additive.

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 ('Detect'), a concrete resource ('active-picture crop rectangle'), and an explicit purpose ('exposing probable letterbox or pillarbox bars'). This clearly distinguishes it from generic detect/analyze siblings such as detect_silence or detect_scene_edits.

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?

The intended use case is implied by the letterbox/pillarbox mention, but there is no explicit guidance on when to use this tool versus alternatives like crop_clip or inspect_media_streams. No when-not-to-use or alternative routing is provided.

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