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

No annotations exist, so the description carries the full burden; it does disclose the return shape (three quartiles) and an important operational fact, the free-trial call limit per signed wallet. It omits the quartile interpolation method (inclusive vs exclusive), minimum data requirements, and error/edge-case behavior for small or malformed datasets — meaningful gaps for a statistics tool.

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?

Three short sentences, operation stated first, then input, then output, then pricing. Slight redundancy between 'Quartile: Calculate quartiles' and 'returns the three quartiles', but nothing wasteful enough to harm usability.

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?

With no annotations, no output schema, and 0% parameter coverage, the description needed to explain input encoding and disambiguate the two overlapping parameters. It does neither, so an agent cannot confidently construct a call from the definition alone.

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% and both parameters ('data' and 'values') are bare strings with no format described. The description says 'Provide values', which points at one parameter but never explains what 'data' is for, whether both are required (schema says 0 required), or how the list should be encoded.

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 ('Calculate quartiles (Q1, Q2 median, Q3) of a dataset') so the operation is unambiguous. It does not, however, distinguish itself from tightly related siblings such as x402-median, x402-percentile, x402-iqr, or x402-five-number-summary, leaving overlap resolution to the agent.

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 guidance and no named alternative, even though the sibling list contains several near-duplicate statistics tools. The only conditional text is a pricing note ('5 free trial calls per signed wallet'), which is not usage guidance for the operation itself.

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