Mx Build Cfdi

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 honestly states that the output is unsealed, omits Sello/NoCertificado/Certificado, and that validation on the output should report exactly those three missing attributes. It also documents RFC validation behavior as a validation error rather than a generated document.

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 dense but every sentence earns its place. It is front-loaded with the core purpose, then adds exclusions, validation behavior, workflow, and return shape without unnecessary filler. Code formatting and structured bullets improve scannability.

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 complex nested-object tool with no annotations, the description is remarkably complete. It covers model validation, RFC validation behavior, sealed vs unsealed output, expected downstream validation results, and the return dict including the total computation formula. An agent can select and invoke this tool correctly with confidence.

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?

The input schema only describes comprobante_data as an object matching a schema, but the description adds substantial meaning: full field list reference, seller/buyer as MXEmisor/MXReceptor, lines as CFDIConcepto, and RFC validation via TaxIdentifier.validate_mx_rfc. This is critical because the schema uses additionalProperties: true and does not enumerate fields.

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 ('Build'), a specific resource ('CFDI 4.0 Comprobante XML'), and a clear scope ('Ingreso or Egreso'). It also distinguishes itself from the sibling mx__build_pago by explicitly excluding Pago documents, making tool selection unambiguous.

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 says when not to use this tool ('For tipo_de_comprobante="P" (Pago), use mx__build_pago instead'), and it names the follow-up tool mx__seal_cfdi for sealing. It also explains what mx__validate_cfdi should report, giving clear workflow guidance.

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