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

With no annotations provided, the description carries the full behavioral burden. It does a good job by disclosing the hard prerequisite that the clip must already exist and the special behavior that reusing a clip filename causes the editor to auto-assign a fresh id. It does not mention return values, failure modes, or permission requirements, but for a simple additive operation these are less critical gaps.

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 and well-structured: the core action comes first, followed by the prerequisite and a practical usage tip. Every sentence earns its place without unnecessary elaboration.

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?

Given the 100% schema coverage and the relatively simple flat parameter set, the description provides enough context for an agent to call the tool correctly: the non-obvious prerequisite and the duplication behavior are both explained. The absence of an output schema means return shape is not described, but that is a minor gap for this kind of additive operation.

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 baseline is 3. The description adds real value for the clip parameter by specifying the upload path and the duplicate-by-reuse mechanism, which are not derivable from the schema alone. It does not add meaning for x, y, width, height, or name, but the schema already documents those adequately.

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 states the specific action and resource: 'Add a video layer.' The 'video' modifier distinguishes it from sibling tools like add_image_layer and add_text_layer, and the duplicate-by-reuse note further clarifies what this tool is for.

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?

It clearly explains the prerequisite that the clip must already exist at a specific storage path and gives the upload endpoint. It also provides guidance for duplicating an existing layer by reusing the clip filename. It does not explicitly name sibling tools or state when not to use it, so it misses the exclusionary guidance that would make it a 5.

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