create_water_zone

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

Annotations already flag idempotentHint=false, but the description adds concrete meaning: every call adds another zone even with a duplicate label, and 'Nothing is saved' discloses the persistence gap. The 'unrotated' transform is also a behavior not visible in the schema, which exceeds annotation coverage.

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 action is front-loaded, followed by caveats and linkage. Slight redundancy: the return values are mentioned twice ('Returns actor_label, actor_name and has_water_mesh' then a 'Returns: {...}' block), which wastes a sentence.

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 spawn tool with no output schema, the description covers the operation, non-idempotency, persistence state, and how to wire the result into water bodies, and it inlines the return shape. It is largely self-sufficient, though it omits any note on undo/selection or required editor context.

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 description coverage is 100%, so both parameters are already documented. The description adds only the implicit note that there is no rotation parameter (always unrotated), which is marginal value over the schema's own location/label descriptions. Baseline 3 is appropriate.

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 (spawn) plus resource (AWaterZone actor) and matches it to the editor world, with the exact transform behavior ('at location, unrotated') and label assignment. It clearly distinguishes itself from the water-body siblings (create_lake_water_body, etc.), which create bodies rather than zones.

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?

Provides concrete workflow context: link bodies via water_zone_label of create_lake_water_body and its siblings, implying this zone must exist first. However, it never explicitly states when to prefer this over alternatives or when-not to call it, so it stops short of full routing guidance.

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