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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe read-only operation. The description adds the behavioral constraint that it does not provide prices, which is useful context beyond the annotations. However, it doesn't describe return format or edge cases (e.g., what happens with invalid terms or mixed units), but with annotations covering the safety profile, a 3 is appropriate.

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 single, dense paragraph that front-loads the core purpose ('Definitions of precious-metal terms') and then lists the exact scope. The exclusion ('No prices (use cotation)') is placed at the end, which is slightly less ideal than front-loading it, but the overall structure is efficient with zero wasted words.

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 tool has 8 parameters, no required parameters, and an output schema exists. The description covers the main use cases (definitions and conversions) and the key exclusion (no prices). It doesn't explain how the parameters combine (e.g., which parameters are needed for a conversion vs a definition), but the output schema and the description's conversion formulas provide enough context for an agent to call it correctly. A 4 is appropriate given the tool's moderate complexity and the presence of an output schema.

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 description coverage is only 38%, so the description must compensate for the 5 undocumented parameters (onces, terme, carats, langue, grammes, milliemes). The description does explain the conversion relationships (weight + fineness → fine metal, troy ounces ↔ grams, carats ↔ thousandths), which adds meaning to those parameters. However, it doesn't explicitly map each parameter to its role, and the 'terme' parameter is only documented in the schema. The description adds value but doesn't fully compensate for the coverage gap.

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 verb ('Definitions') and resource ('precious-metal terms'), and enumerates the exact scope of terms and conversions. It also explicitly distinguishes itself from the sibling tool 'cotation' by stating 'No prices (use cotation)', which differentiates it from a likely price-related sibling.

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 clearly states what the tool does (definitions and conversions) and explicitly says 'No prices (use cotation)', which routes the agent away from this tool when prices are needed. It doesn't explicitly state when to use it vs other siblings like 'regles_gsc' or 'piece', but the scope is clear enough that an agent can infer when to use it.

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