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

Annotations already establish the safety profile (readOnly, idempotent, non-destructive, closed-world), so the burden is light. The description adds the useful qualifier that expected return is 'before-tax' and conditional/optional, but says nothing about return format (probability vs. percentage) or how coverage is expressed.

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 with the primary output (jackpot coverage) front-loaded ahead of the secondary one. Slightly dense phrasing, but no wasted clauses.

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 three-parameter calculation tool with no output schema, the description stops short of describing what the numeric results look like (probabilities, expected value, coverage units) or the relationship between ticket counts and likelihood. It is adequate to invoke the tool but not to interpret its results.

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 67%, with the 'tickets' and 'jackpotCash' semantics already elaborated in the schema itself ('different combinations in the SAME drawing', 'required to compute expected ticket return'). The description echoes those concepts but adds no syntax or format detail beyond them, so it only marginally compensates for the coverage gap.

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 ('Calculate') and two concrete outputs: jackpot coverage for distinct combinations in one drawing, and optional before-tax expected ticket return. This differentiates it in spirit from payout/share siblings, though it never names an alternative tool. Clear purpose, but sibling differentiation is left implicit.

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?

Usage is only implied — the mention of 'distinct combinations in one drawing' and an 'optional' expected-return calculation hints at when each mode applies, but there is no explicit when-to-use/when-not guidance and no pointer to calculate_lottery_payout or calculate_pool_share. The agent must infer routing from the sibling names alone.

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