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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds nothing beyond that: no note on rounding behavior, currency/tip conventions, or whether the bill includes tax or service. Given the low bar set by rich annotations, this is a weak contribution.

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 short sentences, front-loaded with the core operation. The second sentence is navigational and slightly off-topic for a tip calculator, but it is not wasteful enough to undermine the structure.

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 an output schema present, return values need no explanation, and the three required params are fully covered by the schema. The remaining gap is disambiguation: in a sibling set containing calculate_tip and calculate_tip_worldwide, the description never tells the agent which tip tool applies when.

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%, so all three parameters (bill_amount, tip_pct, num_people) are already documented with types and bounds. The description restates the concepts loosely ('restaurant bill', 'per-person') but adds no unit, range, or convention detail beyond the schema baseline.

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: calculating tip plus the per-person split for a restaurant bill. The 'per-person' framing does differentiate it somewhat from calculate_tip, but the description never names that sibling or explicitly contrasts scope with it.

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 only routing hint is 'See list_bundles for related vie-quotidienne calculators,' which points at a browsing tool rather than explaining when to pick this over calculate_tip, calculate_tip_worldwide, or any of the other tip-adjacent siblings. No prerequisites, no when-not-to-use.

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