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

Annotations already establish readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description's burden is lower. It adds useful context about the output standard and input source, but does not describe behaviors like strict validation, error handling, or how the XML is returned.

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, front-loaded sentence with no filler. It states the key compliance standards upfront and lists the essential input categories economically.

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 description names the exact output artifact and standard, and the schema handles parameter documentation thoroughly. The only notable gap is that it does not specify whether the XML is returned inline, as a file, or how validation failures are surfaced, but for a pure generation tool this is a minor omission.

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 100%, so every parameter is already documented in the schema. The description merely lists the same categories (supplier, customer, line items, VAT) without adding new parameter-level meaning, which aligns with the baseline score of 3.

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 names a specific verb ('Generate'), a precise resource ('UBL 2.1 / Peppol BIS Billing 3.0 e-invoice XML'), and the source fields. This clearly distinguishes it from related siblings like generate_pdf_invoice, review_invoice, or check_peppol_ready.

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 intended use is implied by the task-specific wording: an agent would use this when it needs a compliant Peppol e-invoice XML from structured fields. However, there is no explicit when-to-use guidance, no exclusions, and no mention of alternatives such as generate_pdf_invoice or review_invoice.

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