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

Annotations already declare readOnlyHint and openWorldHint. The description adds meaningful behavioral context: the analysis is based on real 3D geometry (Google Solar), computed via PVGIS, and explicitly states that results are not a regional average or a rule-of-three. It also discloses that the heat map is returned only 'quand elle est disponible', consistent with openWorldHint.

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 a focused paragraph with a strong front-loaded action and output list. The clarification 'ce n'est ni une moyenne régionale ni une règle de trois au m²' earns its place by setting expectations. It is slightly long but every sentence adds value; a 4 reflects good structure with minor room for tighter phrasing.

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 description covers the input condition (French postal address), the computation method, the full set of returned fields, the optional heat map, the estimation_id link to demander_devis, and explicit usage triggers. Since there is no output schema and no other structured description of results, this text carries that burden and does so thoroughly for a 2-parameter read-only tool.

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% and the schema descriptions are already rich, including an example for adresse and a note that type_batiment changes results. The main description emphasizes 'à partir de sa seule adresse postale' but adds no new meaning about either parameter beyond the schema. 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 opens with a specific verb ('Calcule') and a precise resource ('le potentiel photovoltaïque réel d'une toiture'), then lists concrete output fields (kWc, kWh, panneaux, orientation, etc.). It clearly distinguishes itself from siblings by mentioning the estimation_id passed to demander_devis, leaving little ambiguity about its role.

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 explicitly states when to use the tool: 'Utilise cet outil dès qu'un utilisateur demande combien produirait une installation solaire chez lui...' It also gives contextual guidance in the schema about requesting a precise address before calling. However, it does not explicitly say when not to use it or name alternatives, so it stops short of a 5.

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