apply_vignette

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

No annotations are supplied, so the description carries the full burden. It conveys that the operation is a mutation of layer pixels, but does not say whether the effect is destructive or reversible, whether it creates a new layer or edits in place, whether an alpha channel or selection matters, or what 'Returns status dict' actually contains. The mention of the return type is the only extra behavioral hint.

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 effect statement is front-loaded, followed by a compact bulleted parameter list and a one-line return note. No filler sentences, though the bullet block is somewhat list-like rather than integrated prose.

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 four-parameter, zero-required mutation tool with no output schema, the description covers every argument and states the return shape. The remaining gap is the lack of disclosure about destructive-ness and layer/target selection behavior, which matters for an image-editing mutation.

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 0% — properties have only titles and defaults — but the description compensates by documenting all four parameters with meaning and defaults, including the non-obvious shape semantics (1.0 = elliptical, >1 = more rectangular) and softness as fade width. This is genuinely additive over the raw schema.

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 first sentence states a specific verb and resource — 'Apply a vignette darkening effect around the edges of a layer' — which is unambiguous and clearly distinct from sibling effects such as apply_noise, apply_emboss, or apply_drop_shadow. It does not explicitly name alternatives, but the effect name alone is specific enough for an agent to identify it.

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?

There is no guidance on when to use this tool versus other edge or filter effects (e.g. apply_gaussian_blur, gefl_apply_filter), and no stated prerequisites such as whether a layer must exist or be selected. Usage is only implied by the notion of targeting 'the active layer' by default.

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