Validate Mls Message

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

With no annotations, the description carries the behavioral burden and it does so by disclosing the validation mechanism (Schematron), the dependency ('requires the xslt2 optional extra'), and the boundary (no bespoke MLS XSD, no full UBL XSD validation). It does not describe the result structure, but an output schema is present, so that gap is covered elsewhere.

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 front-loaded with the core purpose and adds only two high-signal caveats: the Schematron/XSLT dependency and the XSD scope boundary. Every sentence earns its place with 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?

For a single-parameter validation tool with a complete input schema and output schema, the description covers the method, dependency, and scope boundary. It is complete enough to invoke correctly, though it could optionally name related build/validate siblings for routing.

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 the schema already documents mls_xml_base64 as Base64-encoded MLS (UBL ApplicationResponse-2) XML. The description adds context about Schematron validation but does not explain parameter syntax or encoding beyond what the schema states; baseline 3 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 opens with 'Validate a Peppol Message Level Status (MLS) document,' stating a specific verb, resource, and document type. It distinguishes this from sibling validators like validate_tsr_report and validate_eusr_report by the MLS scope, though it does not name a sibling explicitly.

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 clearly frames the tool as the MLS validation path ('Runs the bundled MLS Schematron rules') and gives an explicit exclusion: 'No bespoke MLS XSD exists — full UBL 2.1 XSD validation is out of scope.' It does not name alternative tools or spell out when-not in comparison to siblings, but the document-type condition is clear.

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