verifactu-qr

url_consulta_json

Append format=json to a VeriFactu QR URL to query the AEAT service and retrieve its response in JSON, without changing the QR code.

Instructions

Añade formato=json a una URL de QR para consultar el servicio de la AEAT en JSON (no va dentro del QR).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "url_qr": "<url_qr>"
    },
    "name": "url_consulta_json"
  }
}

Input Schema

Name	Required	Description	Default
`url_qr`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 18, 2026

TDQS

A3.5/5.0

Behavior3/5

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

No annotations are provided, so the description must carry behavioral disclosure alone. It does disclose the transformation (adding formato=json) and a meaningful constraint (the result is not embedded in the QR), but it is silent on whether a network request to AEAT is actually made, what is returned, or any auth requirement, leaving ambiguity for a service-querying tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single sentence with the action front-loaded ('Añade formato=json a una URL...'), and the parenthetical constraint earns its place by preventing misuse. Nothing is padded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter tool with no output schema and no annotations, the description covers purpose and transformation but omits what the call returns (a modified URL vs. service data) and expected input format. Adequate but with clear gaps given structured fields carry none of the load.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There is one parameter (url_qr) at 0% schema description coverage. The description identifies the input as 'una URL de QR', which matches the field name and adds a little meaning, but gives no format, encoding, or validation guidance for that string.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete action on a concrete resource: it appends 'formato=json' to a QR URL so the AEAT service is queried in JSON. This goes beyond restating the name. It does not, however, explicitly name or contrast itself with siblings like verifactu_qr_url, so the agent must infer the split from the trailing parenthetical.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the note '(no va dentro del QR)' tells the agent that the modified URL is for querying the service rather than for embedding in the QR, which hints at when to reach for this versus the QR-generating sibling. There is no explicit when-to-use/when-not statement or named alternative, so it stays at the implied level.

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

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