preview_vehicle_diagnostics

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so extra credit is for context they cannot carry, and the description supplies it: the exact color semantics of the overlay, the fact that it returns both an image and the preflight report, and the coordinate frame ('Coordinates are draft blocks'). The 'Read-only' restatement is redundant but harmless.

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?

Three sentences, front-loaded with the action and output, then usage, then the alternative route, then the coordinate caveat. The overlay legend is dense but each item is load-bearing for reading the image; no filler sentences.

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?

Output schema exists, so return values need not be explained, yet the description still flags that both an image and the preflight report come back. With rich annotations, 100% param coverage and an explicit sibling alternative, an agent has everything needed to call this correctly on the first attempt.

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; the description earns one extra by adding a coordinate-space guarantee ('Coordinates are draft blocks') that is not in any parameter description and that matters when interpreting the rendered output. It does not otherwise add per-parameter guidance on yaw/layer/pitch, but the schema already handles those thoroughly with defaults and enums.

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?

States a specific verb and resource ('Render a draft with its preflight faults drawn over it') and immediately fixes what makes this render different from plain vehicle previews: the faults overlay. The color-coded overlay legend and the explicit tie to preflight_vehicle's findings let an agent separate this from preview_vehicle, preview_hull, preview_interior and preview_game_vehicle without opening any schema.

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?

Gives an explicit when-to-use ('Use it to see where preflight_vehicle's findings are') and names the alternative along with its argument signature: 'open_in_viewer(design=..., diagnostics=true) gives the player an interactive version.' The selection rule (diagnostic overlay vs. interactive player view) and the upstream producer (preflight_vehicle) are both explicit.

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