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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed world, so the safety profile is fully covered structurally. The description adds the behavioral distinction between cent rounding and whole-dollar round-up, but says nothing about how remainders are distributed across shares or about edge cases like people=1.

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 front-loaded sentence covering the core computation and the two rounding modes, with no redundant or filler text.

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 annotations covering safety, a 100%-covered schema, and an output schema handling return values, the description needs little more. It is nearly complete for a simple calculator, with only minor ambiguity around how non-divisible amounts are allocated between the listed people.

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 100% and every parameter carries its own description with bounds and defaults, so the schema does the heavy lifting. The description restates share splitting and rounding but adds no syntax, format, or constraint detail beyond what the schema already documents, making the baseline 3 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 gives a specific verb (Calculate) and resource (bill tip and equal per-person shares) and names the two rounding modes it supports. No sibling tool covers tips, so an agent can immediately recognize this as the tip-calculation tool.

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 by the tool's name and the phrase 'bill tip'; there is no explicit when-to-use statement and no mention of alternatives such as percentage_calculator or unit_price. Adequate for a self-evident calculator but no routing guidance.

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