set_decal_fade_screen_size

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

Annotations already declare write, idempotent, non-open-world behavior, so the safety profile is covered. The description adds the semantic meaning of the value and, importantly, the return shape { actor_label, fade_screen_size } that no output schema provides, which is genuinely useful context beyond the annotations.

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?

Two tight sentences with the core action front-loaded, plus a returns line that earns its place given the absence of an output schema. No filler.

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 two-parameter, fully-schema'd setter with annotations covering the safety profile, the description supplies purpose, value semantics, the getter relationship, and the return shape. Nothing an agent needs to call it correctly 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 both parameters (actor_label, fade_screen_size with its 0..1 meaning) are already documented in the schema. The description's gloss of the fade fraction largely restates that, so the baseline of 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 and resource (set FadeScreenSize on a UDecalComponent) and defines the value inline. It explicitly distinguishes itself from the sibling get_decal_info by framing this as the writer for the value that tool reads.

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 reference to get_decal_info establishes clear context (use this to change what that getter reads) and implies the read/write pairing. It stops short of explicit when-not conditions or pointing at the other set_decal_* siblings, so it is clear but not exhaustive.

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