set_fill_color

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does not explain side effects (e.g., whether existing fills are replaced), behavior when alpha is omitted, error conditions for unsupported node types, or reversibility. This is a significant gap for a mutation tool.

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 description is a single sentence and quickly conveys the core action, achieving conciseness. However, the grammar is awkward ('can be TextNode or FrameNode' lacks a relative pronoun), which slightly detracts from structure and readability.

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?

Given the lack of annotations and output schema, and the simple parameter schema, the description is still incomplete. It does not address important context such as what happens to existing fills, how alpha defaults, or what errors occur for invalid node IDs/types. The description only states the basic action, leaving gaps for an agent to infer behavior.

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?

The input schema covers all parameters with descriptive text (100% coverage), so the description does not need to add parameter meaning. The description itself adds no parameter-specific context, so the baseline score 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?

The description clearly specifies the action (set fill color) and the resource (a node in Figma), and distinguishes from the sibling set_stroke_color by naming 'fill color.' However, the phrase 'can be TextNode or FrameNode' is awkwardly phrased and could be interpreted as a constraint or a capability statement, slightly reducing clarity.

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 description provides some usage guidance by indicating supported node types (TextNode or FrameNode), which implies when the tool is appropriate. However, it does not explicitly mention alternatives like set_stroke_color for stroke colors, nor does it state exclusions or prerequisites beyond node type.

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