Fakturai — German E-Invoice (ZUGFeRD / Factur-X / E-Rechnung)

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

The description explains what is checked but does not disclose behavioral traits like whether the operation is read-only or any potential side effects. Since no annotations are provided, more transparency would be beneficial, but the description is not misleading.

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?

Two concise sentences: first defines the action, second provides usage guidance. No unnecessary words; every sentence adds value.

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 absence of parameters and the existence of an output schema, the description sufficiently covers the tool's purpose and usage context. It explains what to check and when to use it.

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?

There are no parameters, and the schema description coverage is 100%. Per the rubric, 0 parameters receive a baseline of 4. The description adds context but does not need to explain parameters.

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 'Check the e-rechnung engine health' with specific items (KoSIT + Mustang daemon status, dependency version pins vs latest releases). This distinguishes it from sibling tools generate_einvoice and validate_einvoice, which have different purposes.

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 explicitly recommends usage 'before bulk invoice generation', providing a clear context. It does not list alternatives or when not to use, but the guidance is specific and actionable.

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

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

No annotations are provided, so the description carries full burden. It discloses that every returned invoice has passed the KoSIT acceptance gate, which is a strong behavioral guarantee. It does not mention idempotency, side effects, or authentication needs, but for a generation tool, this is adequate.

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?

Two sentences, front-loaded with purpose, includes return values and validation guarantee. No wasted words; keywords for search are appended.

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 complexity (generating a validated e-invoice with specific format) and presence of an output schema, the description is largely complete. However, it lacks any detail on input parameter structure, which would help an agent form correct calls.

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 0%, and the description does not explain the structure or required fields of the two parameters (invoice_json, seller_profile). The parameters are complex objects with additionalProperties, but the description adds no meaning beyond their names.

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 it generates a KoSIT-verified ZUGFeRD/Factur-X German e-invoice, specifies return values (pdf_b64, invoice_number, validation_report), and mentions it passes the official German government acceptance gate, distinguishing it from siblings like compliance_status and validate_einvoice.

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 use for generating a validated e-invoice, and the sibling tools suggest alternatives for compliance checking and validation. However, it does not explicitly state when to use this tool over others or specify exclusions.

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

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

With no annotations, the description discloses that the tool performs multiple validations and requires no authentication. However, it does not specify whether the tool is read-only, if it has side effects, or any rate limits. The behavioral disclosure is adequate but not exhaustive.

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 concise, using a single sentence plus a keyword list. It is front-loaded with the purpose. Slightly verbose with the keywords, but overall efficient.

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 description covers the tool's purpose and validation steps, but does not describe return values or error handling. Since an output schema exists (not shown), the lack of return value description is partially mitigated. Still, for a validation tool, more details on output structure would be helpful.

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 0%, so the description must compensate. It explains that 'content' accepts base64-encoded PDF or raw CII XML, but does not mention the 'content_format' parameter (which defaults to 'pdf_b64') or its allowed values. Partial compensation.

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 the tool validates ZUGFeRD/Factur-X/E-Rechnung invoices and lists the three specific checks (PDF/A, EN 16931 Schematron, KoSIT acceptance gate). It distinguishes from siblings (compliance_status and generate_einvoice) by focusing on validation of existing invoices.

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 mentions it is for validating existing invoices and that no authentication is required, but does not explicitly state when to prefer this tool over sibling tools like compliance_status. Usage context is implied but not complete.

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