Paint: Bucket fill / recolour

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

With annotations only declaring the safety flags, the description adds real behavioral context beyond them: the meaning of tolerance as summed channel distance, that contiguous:false affects every matching pixel of the layer, and that mode:'replace' swaps rather than overpaints. It stops short of discussing return/preview behavior or cost on large canvases.

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-loads the core identity ('Paint bucket.'), then devotes each sentence to a distinct parameter behavior with no filler. The closing line about layers/filters/undo is slightly generic but still useful orientation.

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 12-parameter tool with no output schema, the description foregrounds the confusing semantics and relocates return-format detail to the preview parameter. What an agent needs to invoke a bucket fill correctly is essentially present.

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 covers ~50% of params by description, and the prose compensates by explaining the three undocumented non-obvious ones (tolerance, contiguous, mode) with concrete examples ('60 ≈ shades of the same hue'). x/y/color are self-evident and blend/opacity/preview already carry schema descriptions.

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?

Opens with a specific verb+resource, 'Paint bucket', which unmistakably identifies a flood-fill/recolour operation and implicitly separates it from the line/rect/brush/path siblings. It does not explicitly name a contrasting sibling, keeping it just short of a 5.

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 is implied rather than stated: it notes the canvas is 'created with paint_canvas' and that layers/filters/undo behave uniformly, but gives no explicit when-to-use-this vs paint_pixels/paint_rect guidance or prerequisites. Adequate but with clear gaps.

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