video_index

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

Annotations are absent, so the description bears the full burden of behavioral disclosure. It lists the pipeline steps (frame extraction, ASR, VLM) but fails to mention computational cost, processing time, potential errors, or whether the video file is modified. The read-only nature is implied but not explicit.

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?

The description is compact: a one-sentence summary followed by a parameter list. There is no fluff or redundancy beyond repeating parameter names from the schema, but the added Chinese annotations earn their place. The main functionality 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?

An output schema exists, so return value details are covered. The description explains the processing pipeline and all parameters at a basic level, but it omits important contextual details such as supported video formats, resource requirements, failure modes, or performance expectations. It is adequate for a basic invocation but not for robust selection and planning.

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 0%, so the description must compensate. It does add Chinese labels to all six parameters, which clarifies their meaning. However, the labels are terse; for example, 'task' is just 'analysis task description' with no details on expected task formats or examples, and the relationship between fps and max_frames is left ambiguous.

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 clearly states the tool's composite function: frame extraction, ASR transcription, VLM visual understanding, and timeline output. This distinguishes it from sibling tools like audio_transcribe or vision_inspect by explicitly combining multiple modalities, though it doesn't name those alternatives.

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?

No guidance is provided on when to use this tool versus alternatives such as audio_transcribe for speech-only tasks or vision_inspect for image analysis. The description assumes the user already knows the appropriate context, offering no exclusions or prerequisite conditions.

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