Build and edit terrain

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

Beyond annotations (which already flag destructive/non-idempotent), the description discloses that `fill` applies all solids as a single undo step, that carving is done by filling with material Air (not a special mode), that `clear` on everything requires confirm=true, and that `stats` cannot report terrain location. It also warns about the 4-stud voxel quantization and that nothing thinner than ~4 studs survives — real behavioral constraints an agent cannot infer from the schema.

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?

Front-loaded with a one-line summary followed by op-specific paragraphs; nearly every sentence carries actionable information. It runs long and a few clauses (e.g. the FillBall aside) are conversational, but the length is justified by the tool's four-op complexity.

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?

With no output schema, the description steps in to cover return-relevant behavior (stats reports only whether terrain exists), the fallback for visualizing shape (screenshot), coordinate/units conventions, and the voxel-grid limitation. An agent has everything needed to choose an op and call it 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?

Schema coverage is 100%, so the baseline is 3, but the description adds genuine meaning: the per-shape parameter requirements (block/wedge need size, ball needs radius, cylinder needs radius+height), positions as the centre of the solid in studs, and the Air-carve convention. Much of this is mirrored in the schema descriptions, so it is additive rather than essential.

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 opening line names specific verbs (fills, repaints, clears) and the exact resource (Roblox terrain), then enumerates concrete use cases (hills, water, caves, roads). It also explicitly separates itself from the instance-based siblings: 'none of the instance tools reach it: there is nothing to create, no path for find, and no property for modify.'

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?

Each op gets a when-to-use: `fill` for building, `replace` for swapping material while leaving shape intact, `clear` for emptying, and `stats` explicitly recommended as the first call in an unfamiliar place. It names the alternative route (`execute_luau` FillBall calls) and frames itself as the preferred path over it.

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