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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds domain context about separate France and Switzerland/Europe data volumes, but does not add operational behavior such as auth, pagination, rate limits, or response ordering.

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 purpose is front-loaded, but the description is a single long sentence with nested parenthetical detail that duplicates much of what the output schema likely provides. It is information-dense but less structurally clean than an ideal description.

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 rich annotations, an output schema, and zero parameters, the description is largely complete for a read-only listing tool. It explains the plan data and the important France versus Switzerland volume distinction, though it could better address ordering or when to prefer get_plan.

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?

The tool takes zero input parameters, and the rubric sets a baseline of 4 for no-parameter tools. There are no parameter semantics to clarify, so the description neither helps nor harms this dimension.

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 gives a specific verb and resource: 'Liste les forfaits Flytel commercialisés.' It also enumerates the returned plan attributes, making the tool's scope clear. However, it does not distinguish this listing tool from siblings like get_plan or compare_plans, so it falls short of a 5.

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?

There is no guidance on when to use list_plans versus alternatives such as get_plan or compare_plans. The listing intent is implied, but no explicit when-to-use, when-not-to-use, or alternative routing is provided.

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