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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered. The description adds the return shape and the legal-domain constraint of the French IRL index, but says nothing about the calculation rule (e.g. whether it caps the increase) beyond what the input fields imply.

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?

Three short sentences, front-loaded with the core action, followed by the return shape and a cross-reference. Nothing is padded or redundant.

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 is simple, an output schema exists, and the description names the calculation basis and return fields, so it is largely complete. The one minor gap is that it restates return values already in the output schema instead of explaining the IRL index or its source.

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%, with each parameter documented ('Latest published IRL', 'IRL at lease start', 'Current rent EUR'), so the baseline is 3. The description contributes no additional parameter meaning beyond the schema.

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 (calculate rent increase allowed by the French IRL index), which is more precise than most of the sprawling calculate_* siblings. It does not explicitly differentiate itself from other rent-related siblings such as calculate_rent_ratio, but the domain framing (French IRL) makes the intent unambiguous.

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 pointer to list_bundles for related 'finance-france' calculators, which is a discovery aid rather than a when-to-use statement. There is no indication of when this tool is appropriate versus alternatives, nor any prerequisite about needing an IRL at lease start.

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