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

Goes well beyond the readOnly/idempotent annotations: discloses the external ANAF dependency, local fallback checks, cost (1 credit, waived if ANAF is unreachable), and the exact response shape (valid boolean plus BR-xx/BR-RO-xx codes with bilingual messages). These are precisely the traits an agent needs before spending credits or relying on an open-world call.

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?

Three dense sentences, front-loaded with the core action and rule sets, then validation layers, then return and cost details. No filler, every clause carries operational information.

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, no-output-schema tool, the description covers what the tool does, what it returns, what it costs, and what external dependency it relies on. Nothing material is missing for correct 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?

Only one parameter and schema coverage is 100%, so the schema already documents the xml field including length bounds and accepted document types. The description restates UBL 2.1 invoice/credit note scope without adding format, encoding, or size guidance beyond the schema, so the baseline 3 applies.

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?

States a specific verb (validates) and resource (UBL 2.1 invoice/credit note against RO e-Factura CIUS-RO rules), and names the rule sets used (XSD + Schematron). Clearly distinct from siblings like parse_efactura or generate_efactura.

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?

Gives clear context for use (validating an already-built e-Factura XML, no ANAF account required) and implies it is the check step before submission. It does not explicitly name alternatives such as parse_efactura or when not to use it, so it stops short of a 5.

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