set_fill_color

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

No annotations are provided, so the description carries the full burden. It discloses the supported node types but does not describe behavior for unsupported types, whether it replaces existing fills, the default alpha when 'a' is omitted, or any error handling. For a mutation tool, this is a significant gap.

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 with no unnecessary words. The phrasing 'in Figma can be TextNode or FrameNode' is grammatically awkward, but it is concise and to the point.

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?

This is a simple tool with 5 parameters and no output schema. The description covers the basic purpose and node type restriction, but it does not address edge cases such as unsupported node types, default alpha behavior, or return values. It is adequate but has clear gaps.

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 100%, so the baseline is 3. The description adds a constraint on nodeId by specifying the node must be a TextNode or FrameNode, which goes beyond the schema's generic description of 'nodeId'. This extra meaning justifies a 4.

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 states the tool sets the fill color of a node and specifies that the node can be a TextNode or FrameNode. It uses a specific verb and resource, and the 'fill color' scope distinguishes it from sibling tools like set_stroke_color.

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 does not explicitly say when to use this tool versus alternatives, but the 'fill color' wording implies it is for modifying fill rather than stroke. No alternatives or exclusions are mentioned, so usage guidance is only implied.

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