add_black_video

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

With no annotations, the description carries the full behavioral burden. It doesn't say whether the clip is inserted or overwritten, whether it requires an active sequence or unlocked track, what default properties the black video gets, or what is returned. 'Add' implies mutation but nothing about side effects is disclosed.

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 short sentence with the verb and target front-loaded; nothing is padded. It is arguably too terse rather than verbose, but every word present earns its place.

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?

For a mutation tool with no annotations, no output schema, and three positional parameters, the description leaves key questions open: insertion vs overwrite behavior, required context (active sequence, track state), and the resulting clip's defaults. It is too thin given the complexity.

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% — duration, startTime and trackIndex are each documented in the schema. The description adds nothing about parameter meaning, so the baseline 3 applies.

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?

Names a specific verb and resource ('Add black video ... to the timeline'), so the action is unambiguous. It doesn't distinguish itself from similarly-generative siblings such as add_color_matte or add_adjustment_layer, and the parenthetical '(slug)' is unexplained jargon that adds no clarity.

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?

There is no statement of when to use this versus add_color_matte, add_bars_and_tone, or add_clip_to_timeline, and no prerequisites (e.g. an active sequence must exist). The agent must infer the use case from the name alone.

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