fill_area

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

Description discloses it is a destructive operation (replaces pixels) but does not mention undo behavior, selection interaction, or whether it modifies the file immediately. Given no annotations, description partially fulfills transparency but lacks details about side effects.

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?

Single, clear sentence with no fluff. All information is front-loaded and efficient.

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?

Minimally complete for a 6-parameter tool with no annotations or output schema. Explains core action but omits return value, error cases, and details about frame and layer handling. Additional context (e.g., if cancelable, if requires selection) would improve completeness.

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?

Description adds meaning for x, y (starting coordinates), color (fill color), and layer (target layer). However, frame is not explained despite having a default, and layer's null default is not clarified. With 0% schema description coverage, description partially compensates but leaves gaps.

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?

Description clearly states flood fill operation with specific verb 'replace' and resource 'contiguous region of matching colour'. It identifies starting coordinates (x,y) and target layer. However, it does not explicitly state that the color to be replaced is the pixel color at (x,y) before the fill, though it is implied.

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?

No guidance on when to use this tool vs alternatives like fill_layer, draw_pixels, or other painting tools. No prerequisites, limitations, or context (e.g., file must be open, layer must exist) are mentioned.

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