Qualifizierte Bestätigung nach §6a UStG (BZSt eVatR). Prüft die USt-IdNr des Geschäftspartners und vergleicht Name, Ort, PLZ und Straße mit den offiziellen Daten des Mitgliedstaats. Ergebniscodes pro Feld: - A = Übereinstimmung - B = Keine Übereinstimmung - C = Nicht angefragt - D = Vom Mitglieds...
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AI agents call qualified_confirmation to retrieve information from Ustidnr without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though qualified_confirmation only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"qualified_confirmation": {}
}
}See the full Ustidnr policy for all 3 tools.
These attack patterns abuse exactly the kind of access qualified_confirmation gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Qualifizierte Bestätigung nach §6a UStG (BZSt eVatR). Prüft die USt-IdNr des Geschäftspartners und vergleicht Name, Ort, PLZ und Straße mit den offiziellen Daten des Mitgliedstaats. Ergebniscodes pro Feld: - A = Übereinstimmung - B = Keine Übereinstimmung - C = Nicht angefragt - D = Vom Mitgliedstaat nicht unterstützt Args: own_vat_id: Eigene deutsche USt-IdNr (z.B. DE123456789). partner_vat_id: USt-IdNr des Geschäftspartners. company_name: Erwarteter Firmenname des Partners. city: Erwarteter Ort des Partners. zip_code: Erwartete PLZ des Partners. street: Erwartete Straße des Partners.. It is categorised as a Read tool in the Ustidnr MCP Server, which means it retrieves data without modifying state.
Register the Ustidnr MCP server in PolicyLayer and add a rule for qualified_confirmation: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Ustidnr. Nothing to install.
qualified_confirmation is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the qualified_confirmation rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for qualified_confirmation. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
qualified_confirmation is provided by the Ustidnr MCP server (mavengence/ustidnr-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 3 Ustidnr tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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