vfx_viewer

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

With no annotations, the description carries the full behavioral burden and does well: it discloses once-per-machine startup, the port environment variable and default, live library following, Auto bake behavior, and Export side effects. It does not cover error handling, lifecycle/stopping behavior, or auth, but the core behavior is substantially transparent.

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 front-loaded with the action and return value, then follows with useful feature and behavior context. It is somewhat lengthy and includes a dense feature inventory, but the information is structured and largely 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?

There is no output schema, so the description appropriately explains that it answers the URL, along with port selection and live-update behavior. Its main gap is not clarifying lifecycle or error cases, but it is complete enough to call the tool correctly.

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?

The tool has zero parameters, so the baseline is 4 and no parameter explanation is required. The description correctly avoids inventing parameter semantics and instead focuses on invocation behavior and configuration via environment.

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 a specific verb and resource: it 'Starts the local lab page' and 'answers its URL', making the core purpose clear. It does not explicitly differentiate itself from siblings such as vfx_preview or vfx_render, so it falls short of full sibling-distinguishing 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?

It provides implied usage context ('for the artist to open in a WebGPU browser', 'once per machine') but gives no explicit when-to-use versus alternatives or when-not-to-use guidance. The agent must infer that this is the live interactive viewer rather than the render/preview/bake siblings.

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