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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the safety burden is lifted. The description adds real behavioral context beyond them: the fixed PPP table (FR=0.79, US=1.0, CH=1.36, etc.) tells the agent which countries are supported and that rates are hardcoded rather than live, plus the returned field names.

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 sentences, zero filler, and the core purpose plus the numeric parameters are front-loaded before the optional sibling pointer. Every clause earns its place.

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, fully-described calculation with an output schema present, the description covers purpose, inputs and result shape. The only minor gap is that it does not state the currency assumption for the salary input or whether rates are periodically updated.

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 the baseline is 3, but the description goes further by mapping each country enum code to its PPP factor — meaning that exists nowhere in the schema and directly affects how the salary argument is interpreted. That is genuine additive semantics.

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+resource ('compare salaries across countries using PPP') and immediately scopes it with the exact PPP factor set in use. An agent can distinguish this from calculate_currency_exchange or calculate_purchasing_power without opening the schema.

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 guidance is a cross-reference ('See list_bundles for related vie-quotidienne calculators'), which points at discovery rather than telling the agent when this tool is the right choice versus sibling converters. No explicit when-to-use or when-not-to-use condition is given.

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