scene_update_prefab

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

Goes well beyond the destructiveHint=true annotation: the prefab keeps its id, components and attached graphs, trigger and option-tab areas grow with scale, editor-placed entities retain their own scale, and mechanism assets and creatures cannot be swapped. These are non-obvious side effects an agent could not 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 the change operation, then progressively deeper detail; nearly every clause carries a constraint or example. The colon-chained sentence structure makes it denser than it needs to be, but little is wasted.

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 destructive six-parameter mutation with no output schema, the description covers preservation semantics and side effects thoroughly. The gap is that mapPath and outputName — presumably how the modified save copy is written — are entirely unexplained, which matters for a tool that writes state.

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?

With 0% schema coverage the description must carry the load, and it explains four of six parameters richly — '1 = natural size of the asset', scale accepts a scalar or [x,y,z], asset accepts an id or unique name, health is the base health as in scene_add_prefab. mapPath and outputName are never mentioned, leaving the destination of the 'copy of a save' ambiguous.

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?

Specific verb plus resource ('Change a prefab that already exists') with the mutable facets enumerated (scale, asset, health) and the scope narrowed to a copy of a save. It is immediately distinguishable from scene_add_prefab by the 'already exists' framing.

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?

Usage context is concrete — 'the way to make a wall thicker, a coin smaller, or to give a station another look after seeing it in a playtest' — and it points at scene_list_prefabs and scene_search_assets for the id/name lookups. It implies but never states the negative case (use scene_add_prefab when the prefab does not exist yet).

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