Preview Render (Viewport, Constant Lines)

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

With no annotations to fall back on, the description carries the full burden, and it delivers thoroughly. It discloses that the active editor view is temporarily switched to Constant Shading, that it is built freestanding and never inserted, that BaseDraw/camera/time/take are restored in `finally`, and that the result is returned as base64 PNG. This gives the agent an accurate mental model of side effects and safety.

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 but information-dense, with every sentence earning its place: purpose, renderer mode, independence, cleanup, return type, and parameter usage. The most important fact (quick verification render) is front-loaded, and the parameter guidance is packed efficiently without redundancy.

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 tool with no output schema, the description fully covers the return format (base64 PNG inline), side effects (state restoration), and parameter semantics. It explains the key limitations (max 4096, parent directory must exist) implicitly through schema descriptions, and the description itself covers the behavioral contract completely. Nothing an agent needs to decide whether to call this tool is missing.

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 the description only needs to add value beyond the schema, and it does. It explains the behavior of 'view' presets (auto-framed temp camera), the meaning of 'current', and clarifies that save_path still returns the base64 PNG inline. The only minor gap is that the description does not restate the default/range behavior, but the schema already covers that fully.

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 ('preview render') and resource ('Viewport renderer with Constant Shading Lines'), and characterizes it as a quick agent-friendly verification render. It also differentiates itself from the sibling `render` tool by emphasizing freestanding, non-inserted rendering and inline base64 return, so an agent can distinguish when to use this instead.

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 explicitly explains when to use this tool—for quick verification renders—and contrasts it implicitly with other render tools. It provides concrete usage options: 'view' presets for auto-framed temp cameras, 'camera' for named scene cameras, and 'save_path' for disk output, giving clear conditions for each path.

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