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

Annotations already declare readOnlyHint and openWorldHint, and the description goes well beyond that. It discloses that rounding is cash-only, applies after tax, is not free money, and that floating point money is a bug risk. It also clearly states what the tool returns and that the gain is never more than 4 cents. No contradiction with annotations exists.

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?

The description is longer than average but is front-loaded with the core purpose and use cases. The warning and 'WHY DELEGATE THIS' sections are genuinely informative, though the ownership/URL sentence at the end is somewhat extraneous. Overall, most sentences earn their place, but a little trimming would make it tighter.

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 tool with no output schema, the description clearly states what is returned: 'the whole band, the highest price in it, and the free gain in cents.' It also covers domain traps, parameter context, and the rationale for delegating. The agent has enough to decide when to call it and what to expect in response.

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%, so the schema already documents all three parameters. The description adds useful conceptual context around listPrice and taxRatePercent, especially the 'after tax' and 'cash only' behavior, but it does not add significant per-parameter semantics beyond the schema. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'finds every nearby list price that settles to the SAME cash total, and the highest one.' It also frames concrete use cases ('what should I charge' and 'can I price to gain from rounding'), making the tool's identity and value unmistakable. The title reinforces the same behavior without conflicting with the description.

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?

The description explicitly states when to use the tool and what kinds of questions it answers. It also warns against a common misuse ('The move that looks clever and is not') and says the tool 'will not recommend it.' It does not explicitly name sibling alternatives like round_cash_total or rounding_impact, so the routing guidance is strong but not fully exhaustive.

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