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

No annotations exist, so the description carries the full behavioral burden. It does disclose the output semantics (Q3 minus Q1) and the auth/pricing model ('5 free trial calls per signed wallet'), which is genuinely useful context. However, it says nothing about percentile interpolation method, minimum dataset size, or error behavior, and no output schema backs it up.

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 tight sentences that lead with the operation and its formula, plus a short pricing tag. The leading 'Iqr:' label merely restates the tool name and is dead weight, but the rest is efficient and front-loaded.

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 one-parameter calculator with no annotations and no output schema, the description covers purpose, computation, and pricing adequately. The critical gap is input format for the string parameter and what happens with small or invalid datasets, which an agent would need before calling it correctly.

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 0% for the single parameter, which is typed only as a bare 'string', so the description must compensate. 'Provide values array' gives a hint about content but conflicts with the declared string type and leaves the encoding (comma-separated list, JSON array literal, whitespace-delimited) completely unspecified.

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 gives a specific verb and resource ('Calculate the interquartile range (IQR)') and even spells out the formula 'returns Q3 minus Q1 (75th minus 25th percentile)', so the agent knows exactly what computation it performs. It stops short of distinguishing itself from close siblings such as x402-quartile, x402-quartile-deviation, x402-interquartile-mean, or x402-range-stat, which the formula alone only partially disambiguates.

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?

There is no when-to-use or when-not-to-use guidance and no sibling alternative is named, even though the tool list contains several near-duplicate statistics tools (quartile, quartile-deviation, range-stat). The only directive is 'Provide values array', which is an input instruction, not a selection rule.

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