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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuine behavioral context beyond that: the ADEME dataset drops replaced DPEs, so lookups for superseded certificates will fail. It still doesn't say what happens on an unknown number (error vs empty).

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, no filler, and the key identifying detail (the number format) appears early. The opening sentence is slightly convoluted ('The dwelling of a French DPE ... by its ... number') but still readable.

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 one-parameter read-only lookup with no output schema, the description covers the input format, the conceptual return (dwelling + rental verdict), and a data-availability caveat. Only the failure behavior for missing or replaced DPEs is left unstated.

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 0% and the single dpe_number property has no description, so the description must carry the parameter. It does: it specifies the 13-character format and gives a concrete example (2569E0160739C), which is exactly what an agent needs to construct a valid call.

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 names a specific resource (the dwelling of a French DPE) and the retrieval key (its 13-character number, with an example), and it positions itself against the sibling check_rental_compliance by saying it returns the same rental verdict. The verb is only implicit from the tool name, but an agent can still distinguish this tool from its siblings.

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?

Usage is implied: use this when you already hold a 13-character DPE number and want the dwelling plus verdict. The reference to check_rental_compliance hints at a relationship but never states when to choose one over the other, and no prerequisites or exclusions are given.

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