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

The description goes beyond the readOnlyHint annotation by detailing the exact rules and thresholds: 'G banned since 2025, F from 2028, E from 2034', the rent freeze since 25 Aug 2022, and the 10-year validity rule with transitional expiries. It also assures 'Deterministic rules from official thresholds — no AI involved,' which sets expectations. This thoroughly aligns with the readOnlyHint and adds significant behavioral context.

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?

The description is dense but every sentence carries specific information: the summary line, the detailed breakdown of each restriction, and the legal references. It front-loads the main purpose and then expands. It could be slightly trimmed, but given the complexity of the rules, the length is justified.

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?

Given no output schema, the description must explain what is returned, and it does: letting ban status and date, rent freeze, and DPE validity. It covers all three main aspects with precise dates and conditions, and notes the deterministic nature. For a tool with two parameters and clear rules, this is comprehensive.

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% for both parameters, so the schema already explains them. The description adds meaning by linking dpe_issue_date to the validity check ('when dpe_issue_date is provided — whether the DPE itself is still valid') and implicitly defines the DPE class range 'A–G'. It enriches the semantics without restating 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?

The description clearly states the tool's purpose: it returns French rental restrictions (letting ban, rent freeze, DPE validity) based on a DPE class. The verb 'returns' and resource 'French rental restrictions' are specific, and it distinguishes itself from sibling tools that focus on Swiss salary, rent revision, etc., which are unrelated domains.

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 provides clear context for when to use the tool: when a dwelling's DPE class is known and French rental restrictions are needed. It mentions France métropolitaine for the letting ban, and the optional dpe_issue_date for validity. It doesn't explicitly state alternatives, but siblings are obviously different topics, so no confusion arises. Could be improved by explicitly stating not to use for non-French properties.

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