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

With no annotations, the description carries the full behavioral burden and does little with it. It does disclose the t default and a payment-model detail ('5 free trial calls per signed wallet'), but says nothing about return format, numeric-string handling, or what happens with out-of-range t (extrapolation vs clamping).

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?

A single compact sentence front-loads the core behavior, followed by a short promo clause. Little waste, though the emoji trial-offer line is promotional rather than functional and could be trimmed.

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?

No annotations, no output schema, and three parameters with zero schema documentation. For a numeric-computation tool the description should at least clarify input string format and result shape; as written it leaves the agent guessing about both.

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% and all three parameters are typed merely as strings, so the description must compensate. It conveys that a and b are endpoints and t is the interpolation factor with a 0.5 default, which is real added meaning, but it leaves the string encoding (decimal strings? numeric format?) and valid ranges unexplained.

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 and resource ('Interpolate') and spells out the operation: linear interpolation between a and b using t. That is concrete and unambiguous. However, it does not differentiate itself from close siblings such as x402-lerp, x402-lerp-value, x402-interpolation, or x402-map-to-range, so an agent cannot route between them from this text alone.

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 gives no when-to-use or when-not-to-use guidance and names no alternative. The only usable cue is the default t=0.5, which tells the agent the parameter is optional but not when this tool is preferable to the near-identical lerp/interpolation siblings.

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