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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds no behavioral context beyond the purpose: it doesn't state the quartile interpolation method (a materially different result for e.g. Tukey vs linear interpolation), whether input must be pre-sorted, or any minimum data-length requirement beyond the schema's 'Non-empty list'.

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 short sentence with the output set front-loaded and zero filler. It is efficient but borders on under-specified for a statistical tool where method choice affects results.

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?

An output schema exists, so return values needn't be explained, and the input schema is fully documented. The remaining gap is methodological: for a quartile calculator, which interpolation convention is used is essential to interpreting Q1/Q3 and IQR correctly, and the description is silent on it.

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 100%: the single parameter is documented as 'Non-empty list of numbers' and includes a worked example array. The description adds nothing about the data parameter (no ordering, duplicate handling, or size constraints), so the baseline 3 applies when the schema does all the work.

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 (calculate) and names the exact outputs: Q1, Q2 (median), Q3 and IQR. The parenthetical clarifies Q2 equals the median, which helps distinguish it from calculator_median. However, it never explicitly says how this differs from calculator_median, calculator_percentile, or calculator_range in the sibling list.

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 mention of alternatives. An agent choosing between calculator_quartile, calculator_percentile, calculator_median, and calculator_std gets no routing signal. The name alone implies the use case, but nothing in the description resolves the overlap with sibling statistical tools.

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