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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered. The description adds the output field list (count, std_deviation, min, max, range, iqr), which is mild behavioral context, but says nothing about edge cases such as single-value input, precision, or error behavior.

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 compact clauses, front-loaded with the purpose before output and cross-reference. Every sentence is short and purposeful, though listing computed statistics and then a non-overlapping set of return fields creates a small redundancy/ambiguity.

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 pure function with full annotation coverage, a 100%-documented single parameter, and an output schema, the description is adequate. The one real gap is the mismatch between the statistics claimed as computed (mean, median, mode, quartiles) and the return fields listed, which could mislead an agent about the result shape.

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% for the single 'values' parameter, so the schema already carries the meaning. The description adds no constraints (numeric type, minItems=1, ordering) and even omits mention of the input array entirely, leaving the parameter entirely to the schema.

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 (descriptive statistics) and enumerates the computed measures (mean, median, mode, std dev, quartiles), which is far more specific than most siblings. It does not explicitly contrast itself with any sibling, and the enumerated measures don't match the listed return fields, slightly muddying what the tool actually produces.

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 explicit when-to-use or when-not-to-use guidance, and no alternative tool is named for descriptive statistics. The pointer to list_bundles for 'education' calculators is a discovery hint rather than selection guidance, so usage is only implied.

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