validate_mls_message

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that the tool depends on the optional [xslt2] extra, that it uses bundled MLS Schematron rules, and that no bespoke MLS XSD exists. These are meaningful behavioral traits beyond the input schema. It does not describe error behavior or result shape, but the output schema covers return expectations.

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 compact and front-loaded with the main purpose. Every sentence contributes: the first states what it validates, the second explains the mechanism and dependency, and the third clarifies an important scope limitation. There is no redundant or filler language.

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 a single parameter, full schema coverage, and an output schema, so the description does not need to explain return values. It provides the necessary context: document type, validation method, dependency, and scope boundaries. This is complete enough for an agent to correctly select and invoke the tool.

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%, and the input schema already documents mls_xml_base64 as 'Base64-encoded MLS (UBL ApplicationResponse-2) XML.' The description adds a bit of context by identifying the document type as Peppol MLS, but it does not add further parameter-level detail beyond what the schema already provides. 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 clearly states a specific action and resource: 'Validate a Peppol Message Level Status (MLS) document.' This distinguishes it from sibling validation tools like validate_invoice_be, validate_eusr_report, and validate_tsr_report by naming the exact document type. The rest of the description reinforces the purpose by explaining the validation mechanism.

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 implies its usage context by specifying it validates MLS documents and runs Schematron rules. It explicitly notes that full UBL 2.1 XSD validation is out of scope, which is a useful exclusion. However, it does not mention alternatives or provide explicit when-to-use versus when-not-to-use guidance compared to sibling tools.

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