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 behavioral transparency burden. It only states the valid node types but fails to disclose critical behavior such as whether the fill is replaced or appended, what happens if the node has multiple fills, or how the alpha channel behaves when not specified. 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 short sentence and front-loads the main action, but the sentence is grammatically incomplete ('can be TextNode or FrameNode' is a fragment). It could be more polished, but it is concise and does not contain unnecessary filler.

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 5-parameter mutation tool with no annotations and no output schema, the description is too minimal. It does not mention side effects, prerequisites, what the result looks like, or any error conditions. The node type restriction is helpful but insufficient for an agent to fully understand the tool's impact.

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 already describes all five parameters (nodeId, r, g, b, a) with full coverage. The description adds no additional meaning to the parameters. Since schema coverage is 100%, the baseline score of 3 is appropriate; the description does not need to explain parameters further.

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 identifies the action (Set the fill color) and the target resource (a node in Figma), and even specifies valid node types (TextNode or FrameNode). However, the grammar is awkward and incomplete, which prevents a perfect score. It still distinguishes itself from siblings like set_stroke_color by focusing on fill 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?

No guidance is provided about when to use this tool versus alternatives. It does not mention that it should be used for fill colors specifically as opposed to stroke colors, borders, or other properties. The usage context is only implied by the tool name, not explicitly stated.

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