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

The description adds substantial behavior beyond the annotations: it lists changes as field/old/new, re-validates the result, charges $0.05 USDC via x402 only if something was fixed, and advises reviewing changes before sending. These details are not inferable from readOnlyHint/destructiveHint/idempotentHint/openWorldHint alone.

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 usage condition and then efficiently covers what is fixed, what is returned, payment terms, and a review caution. Every sentence earns its place and there is no redundant restatement of the title or schema.

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 two-parameter tool with full schema coverage and no output schema, the description provides enough context to call it correctly: when to invoke it, what it fixes, that it returns a change list and corrected XML, that it re-validates, and that it is paid. Nothing critical is missing.

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 both parameters already have clear schema descriptions. The tool description does not add syntax or format guidance for the xml or profile parameters beyond what the schema provides, so the baseline of 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 states a specific verb and resource ('fixes invoice XML') and lists exactly what it corrects: county/sector/country/currency/unit codes, date formats, VAT-id prefixes, decimals, totals, and VAT. It distinguishes itself from sibling validators by returning corrected XML and listing every change, rather than only reporting validation results.

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 gives a clear triggering condition: use when a validation report lists 'autofix' rules or when ANAF rejected an invoice for codes, dates, or totals. It implies the alternative of manual editing, but does not explicitly name sibling tools or state when not to use this tool.

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