validate_invoice_ae

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

Annotations are absent, so the description carries the full burden, and it does an excellent job: it discloses exact scope metadata values, constant warnings, expected BR-CO-09 behavior on genuine AE invoices, known limitations with UAE TRNs, and the fact that the variant parameter does not change execution. This is far beyond what the input schema reveals.

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 long but every sentence earns its place: purpose, scope limitation, expected warnings, known limitation, conformance caveat, artifact reference, return behavior, and variant semantics are all packed tightly. The most important scoping information appears early, and there is no filler.

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?

Given the tool's complexity and that an output schema exists, the description is complete: it explains exactly what validation is performed, what is excluded, what warnings are always included, why a known rule fires, and how the variant parameter behaves. An agent has enough context to invoke the tool and interpret its scope correctly.

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 coverage is 100%, so the parameters are already well documented; the description adds genuine value by revealing that the variant parameter exists only for interface stability and does not affect which rules run. This is useful semantic detail not inferable from the schema enum alone.

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 opens with a specific verb and resource: 'Validate a PINT AE UBL 2.1 invoice against the CEN EN16931 base Schematron.' It also actively differentiates itself from sibling validation tools by stating what it does NOT check and that it is not a full PINT AE conformance check, so an agent can distinguish it from validate_tdd_ae and related tools.

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 strong when-to-use and when-not-to-use context: it explicitly says this tool covers only the CEN EN16931 base rules, excludes the PINT-AE jurisdiction overlay, and warns that passing documents may still be rejected by a real Peppol Access Point. It does not explicitly name an alternative tool for full conformance checking, which keeps it from a 5.

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