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

Annotations already signal readOnly, idempotent, non-destructive, and closed-world behavior. The description adds meaningful behavioral context by disclosing that the data is indicative, based only on the house's public grid, excludes external market data, carries no advice, and is sampled at one point per day.

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 compact and front-loaded with the core purpose, followed by the supported assets, output indicators, and caveats. It is slightly dense with parentheticals, but every clause contributes useful information and nothing is redundant with the annotations.

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 an agent selecting and invoking the tool, the description covers the period, granularity, asset categories, returned statistics, data source, and advisory limitations. The output schema covers detailed return structure, so the description does not need to repeat it; nothing essential for a correct call 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?

The schema already documents cle values, jours bounds/default, and langue via enum. The description reinforces the 18K default and adds the important 'one point per day' meaning for jours, which is not evident from the parameter name alone. It does not add much about langue, but the enum is self-explanatory enough.

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 that the tool returns the evolution of the house's own published buying grid over 7 to 365 days, with one daily point per dayaca, for specific gold finenesses or listed coins/bars, and lists the summary fields returned. It distinguishes itself from a current-price tool by emphasizing the historical range and the private grid source.

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 gives clear context: this is for historical movement of the company's buyback grid, not current market data. It does not explicitly name cotation as the alternative for current quotes, but the historical period and the 'no external market data' caveat make the appropriate use fairly unambiguous.

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