Add fade in/out

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

With no annotations, the description carries the full burden. It discloses the fade behavior and that audio is included, but does not cover edge cases like what happens when both fade_in and fade_out are omitted, or whether output_path is required for writing. This leaves some behavioral ambiguity.

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 sentence with no fluff, front-loaded with the action. It is appropriately concise.

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?

The tool has four parameters but only one is required. The description lacks guidance on default behavior when optional fade durations are omitted, and whether an output path must be specified. For a video-processing tool, this missing context reduces completeness.

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 100%, so baseline is 3. The description adds context that the fade is 'from black' and at 'start'/'end', clarifying the effect, but does not add significant detail beyond what the schema already provides.

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 fades video and audio in from black at the start and out to black at the end, using a specific verb and resource. It distinguishes itself from sibling tools like trim or convert by focusing on fade transitions.

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 description implies when to use the tool (when a fade effect is desired), but provides no explicit guidance about alternatives or exclusions. Since the purpose is straightforward, an agent can infer usage, but there is no stated comparison with other video editing tools.

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