set_fill_color

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

Discloses default behavior of alpha component and hints at how to achieve transparency. No annotations, so description carries burden; adds value beyond schema.

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 concise sentences, no waste. Front-loaded with core purpose, then key detail about alpha.

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?

Adequate for a simple mutation tool with well-defined parameters. Lacks mention of error conditions or return value, but not critical given 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 already describes each parameter (100% coverage). Description adds slight value by restating alpha default and suggesting alpha=0 for transparency, but mostly redundant.

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?

Describes exactly what the tool does: set the fill color of a node in Figma. Clear verb and resource, differentiated from sibling tools like set_stroke_color or set_gradient.

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 guidance on alpha default and usage for transparency. Does not explicitly contrast with alternative fill-setting tools but context makes it clear for solid colors.

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