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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-obvious domain behavior: the first guess carries the house edge, subsequent guesses pay fair odds, and skips deal a new card without multiplying the payout. It does not discuss invalid-path handling or edge cases.

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 dense sentences with no filler, front-loading what is computed before the payout mechanics. Every clause carries information an agent needs.

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 only two top-level parameters, an output schema covering return values, and annotations covering the read-only/idempotent profile, the description supplies everything else needed to invoke it correctly — the path structure and the payout rules. Minor gaps around malformed paths are acceptable at this complexity.

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 50% and the description compensates by mapping the structure semantically: 'the start card, then each guess and the card that came' ties directly to start and the steps[].guess/next pair. It also explains evaluation ordering and the special meaning of skip, which the schema does not convey. It does not disambiguate the enum values (higher vs higherEqual, equal), leaving that 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 names a specific resource ('Payout and odds of a HiLo path') and clarifies the inputs are the start card plus each guess and resulting card. That is far more specific than the siblings that cover other games (crash odds, slot lookup, chain latest), though it never explicitly contrasts itself with stake_payout_odds.

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: an agent can infer this is for evaluating a completed HiLo sequence, but there is no statement of when to choose it over stake_payout_odds or other odds tools, and no prerequisites or exclusions are given. The domain rules about house edge and skips are behavioral, not routing guidance.

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