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

With no annotations, the description carries full behavioral burden. It does disclose the output: four hues 90 degrees apart and the 0-360 hue range. However, it instructs the agent to 'Provide hue' while the input schema is empty, creating a conflicting and misleading invocation contract. The description should explain that no parameters are accepted.

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 compact sentence that packs the essential purpose, input range, and output spacing without waste. The initial 'Tetradic:' label is redundant with the tool name, but the rest of the sentence earns its place.

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 tool with no output schema and no annotations, the description should fully explain invocation and return values. It states the output concept (four hues 90 degrees apart) but omits the actual return format, any default behavior for missing input, and correct parameter usage. The input mismatch leaves the definition incomplete.

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 defines zero parameters, yet the description explicitly tells the user to provide hue (0-360). This is an invented parameter that does not exist in the schema, so an agent following the description would attempt to pass an argument the tool does not declare. This is worse than a simple omission and severely harms parameter understanding.

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 specific verb ('Generate') and resource ('tetradic color harmony'), and distinguishes itself from sibling color tools by specifying four hues spaced 90 degrees apart. Even with no title, an agent can tell this tool from triadic, complementary, and analogous siblings.

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 implied: an agent can infer this tool is for requesting a tetradic color harmony. However, the description gives no explicit guidance on when to choose this over the many sibling color-harmony tools (x402-triadic, x402-analogous, x402-complementary, x402-monochromatic).

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