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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral context: the results are indicative only and Eurocode 5 / signed CCTP take precedence — a caveat an agent must convey downstream. It does not describe what the check returns (pass/fail per code, findings list), which keeps it from a 5.

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?

Front-loaded with the trigger, then the checked dimensions, then the caveat — dense and efficient with no filler. The one wasted clause is the verbatim echo of the parameter description already present in the schema.

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?

With a single optional nested-object parameter, no output schema and full annotation coverage, the description supplies what's needed: scope, the four check axes, and the non-normative disclaimer. Only a hint about the expected shape of the scene object or the result set is missing.

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?

There is a single optional parameter and schema description coverage is 100%; the description merely restates the schema text ("scene : chevrons {section, fixation, appuis, protection}"). Per the high-coverage baseline, the schema already carries this, so 3 is the ceiling of what the description contributes.

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 states a specific action (VERIFIER LES CHEVRONS) and enumerates the four dimensions checked with their codes (CH-SECTION, CH-FIXATION, CH-APPUIS, CH-PROTECTION). This is markedly more specific than the sibling cao_bim_charpente / cao_bim_fermes / cao_bim_pannes entries, which concern other roof members, so an agent can pick this one without opening a schema.

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?

"Appelez quand vous devez VERIFIER LES CHEVRONS" gives an explicit trigger condition. It stops short of naming alternatives (e.g. cao_bim_charpente for whole-frame checks) or when-not-to-use cases, so it is clear context without routing exclusions.

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