Converts a color between HEX, RGB and HSL, returns complementary and analogous colors and the WCAG contrast ratio against white and black. 0.001 USDC per call via x402.
| Name | Required | Description | Default |
|---|---|---|---|
| color | Yes | Color as #hex, rgb(r,g,b) or hsl(h,s%,l%) | |
| paymentProof | No | Payment proof: USDC tx hash on Polygon or Base (0x...) or Solana tx signature. Omit on the first call to receive the 402 payment instructions, pay, then call again with the proof. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden and does disclose the commercial trait (0.001 USDC per call via x402) and the derived return values, which go beyond a plain conversion. It stops short of explaining the 402 handshake or what happens on malformed color input, though the payment mechanics are covered in the schema's paymentProof description.
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 sentences with zero waste: capabilities front-loaded, commercial constraint second. Nothing repeated or padded.
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 two-parameter, no-output-schema utility the description enumerates what comes back, so an agent knows the return content without an output schema. Minor gap: it does not indicate whether complementary/analogous colors and the contrast ratio are always returned or conditional on input format.
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 both parameters (including the two-step paymentProof flow) are already fully documented in the schema. The description's mention of HEX/RGB/HSL merely mirrors the color parameter's own description and adds no format, default, or validation detail beyond it; baseline 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?
States a specific verb (converts) plus the exact resource and format set (HEX, RGB, HSL), and additionally names the derived outputs (complementary/analogous colors, WCAG contrast ratio). No sibling in the list overlaps this function, so an agent can select it unambiguously.
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?
Usage is only implied by the description of formats; there is no explicit when-to-use/when-not statement or named alternative (closest siblings, case_convert and units_convert, are unrelated enough that no routing is needed). The one piece of real guidance — pricing at 0.001 USDC per call via x402 — is a useful constraint but is stated rather than explained.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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