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

With no annotations, the description carries the full burden and does well: it discloses the fallback behavior for missing t (0.5), clarifies that t=0 is a real weight, and mentions the free trial calls per signed wallet. These are valuable behavioral details beyond a bare operation 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?

The description is a single sentence with a clarifying parenthetical, followed by pricing information. It is front-loaded with the core operation and remains efficient, though the pricing note, while relevant, could be considered slightly extraneous for pure function selection.

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 simple interpolation tool with no output schema and no annotations, the description covers the key aspects: what it does, default behavior, edge cases, and pricing. It is nearly complete, missing only explicit return format details and error conditions, which are minor for this operation.

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 coverage is 0%, so the description must explain the three parameters. It clearly identifies a and b as the interpolation bounds and t as the weight, and it adds crucial semantics: t defaults to 0.5 when missing, and t=0 is a valid value. It does not specify input types (e.g., numbers as strings), but it compensates well for the schema gap.

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 ('Linearly interpolates') and resources ('between a and b by t'), making the purpose immediately clear. It does not, however, differentiate this tool from similar siblings like x402-lerp or x402-interpolate, so it falls short of a 5.

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 no guidance on when to use this tool versus alternatives such as x402-lerp or x402-interpolate. It only describes the operation itself and the default behavior for t, leaving the agent to infer usage context.

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