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

Annotations already indicate readOnlyHint=true inferring a safe read operation. The description adds that it's 'Deterministic official allowance tables — no AI', which explains the computation nature. It also describes the return values (Swiss annual/monthly in CHF, CAF monthly in EUR, differential, year). It doesn't mention any side effects, but for a read-only deterministic calculator, this is adequate. It adds value beyond annotations.

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: first states the purpose and outputs, second adds deterministic nature and return specifics. Every word serves a purpose, no redundancy.

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?

The tool has 3 parameters (all described in schema), no output schema, but the description explicitly lists the returned values (Swiss annual/monthly in CHF, CAF monthly in EUR, differential, data year). It also mentions the deterministic nature and the EU regulation. For a calculation tool with clear inputs, this is complete enough. Could have mentioned edge cases (e.g., max children, age limits) but schema covers those. Overall adequate.

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 parameters are well-documented in the schema. The description adds context about the differential top-up and spouse working in France, which matches the parameter. But it doesn't add significant meaning beyond the schema descriptions. 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 clearly states the tool compares Swiss vs French family allowances for a frontalier, specifies the differential top-up, and lists the exact outputs. It uses a specific verb ('compares') and resource ('family allowances for a frontalier'), and it's distinct from siblings which deal with other legal/financial calculations.

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 implies usage for frontaliers with children comparing Swiss vs French allowances concrete. It doesn't explicitly mention when not to use it or alternatives, but the purpose is specific enough that it's clear this is for cross-border workers. Given the sibling tools are unrelated (net salary, rent revision, etc.), the context is sufficient. It could have explicitly stated 'use this if you are a frontalier with children' but it's implied.

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