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

No annotations are provided, so the description carries the full burden. It discloses that it is format-only and does no math, which is useful, but it does not explain the output format, return value, or any side effects. The inclusion of 'Paid $0.01 USDC Base x402' is confusing and unexplained, detracting from transparency.

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 short and front-loaded with the core purpose, but the sentence 'Paid $0.01 USDC Base x402' is extraneous and seems unrelated to the tool's functionality. It adds noise and reduces overall conciseness.

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 a tool with no parameters and no output schema, the description states the purpose and format but does not specify the return type or format of the output. The payment note is ambiguous and could mislead an agent. It is adequate but not complete for a clear invocation.

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 has zero parameters, so the schema provides no parameter documentation. The description adds meaning by listing the content of the line (designation, quantity/unit, unit price HT), which clarifies what the tool produces. With no parameters, a baseline of 4 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 clearly states the tool's function: it defines a French invoice line with designation, optional quantity/unit, and unit price HT, and explicitly says it is format-only with no line-total math. This distinguishes it from sibling tools that handle calculations or other invoice aspects.

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?

It implies usage for formatting lines rather than computing totals ('Format only, no line-total math'), but does not name specific alternatives or give explicit when-to-use/when-not-to-use guidance. The siblings list exists but no direct reference is made.

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