vroid_set_color

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

With no annotations provided, the description carries the full responsibility of behavioral disclosure. It transparently describes the step-by-step mechanism: scrolling the right-hand panel, clicking the hex field, replacing contents, and pressing Return. It also discloses the limiting condition about the currently open tab. This is a solid level of transparency for a UI automation tool, though it does not mention potential failure modes (e.g., label not found) or side effects beyond the described actions.

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 exceptionally concise—two sentences—and front-loads the purpose in the first sentence. The second sentence packs in the operational steps and the caveat with no wasted words. Every element contributes to understanding, and nothing is redundant with the schema.

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?

The description covers the essential aspects of the tool: its purpose, the detailed interaction sequence, and a critical precondition (correct tab and sub-category). It does not explain error handling or what happens if the label is missing, but given that an output schema exists (though not shown) and the tool is relatively simple, the description is sufficiently complete for an agent to use it effectively.

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?

Both parameters have schema descriptions with examples, so the baseline is 3. The description adds extra meaning by explaining how each parameter is used in the operation: 'label' identifies the row to scroll to, and 'hex' is the value typed into the field. This contextualizes the parameters beyond their simple data type definitions, making the tool easier to invoke correctly.

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 states a clear, specific action: 'Set a colour swatch by typing a hex code into its #RRGGBB box.' It identifies the resource (colour swatch) and the method (typing hex code), and the focus on color differentiates it from sibling tools like vroid_set_slider. The purpose is unambiguous and actionable.

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 a caveat ('Same caveat as sliders: the row must belong to the currently open tab and sub-category') which gives some usage context, but it does not explicitly state when to use this tool versus alternatives like vroid_set_slider or vroid_click. There is no direct 'use this when...' or 'do not use when...' guidance, leaving the agent to infer the appropriate scenario from the tool's purpose.

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