upload_certificate

THE RISK

Medium Risk

Why upload_certificate needs a policy

This is a Write operation because it creates or modifies certificate data reversibly. It is high severity because a compromised or incorrect certificate can block legitimate tax document issuance, disrupt business operations, or enable fraudulent document signing if a malicious certificate is uploaded.

From the tool's definition "Upload or update an A1 digital certificate (.pfx, base64)" - the tool modifies certificate data stored for an empresa (company), enabling fiscal document emission.

Documented attack patterns abuse exactly the kind of access upload_certificate gives an agent:

POLICY

How to control upload_certificate

PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Afip, and nothing reaches the server without passing your rules. This is the rule we recommend for upload_certificate:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "upload_certificate": {
      "limits": [
        {
          "counter": "upload_certificate_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

upload_certificate stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register Mcp Afip — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about upload_certificate

What does the upload_certificate tool do? +

Upload or update an A1 digital certificate (.pfx, base64) for an empresa. Required to emit fiscal documents. It is categorised as a Write tool in the Mcp Afip MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on upload_certificate? +

Register the Mcp Afip MCP server in PolicyLayer and add a rule for upload_certificate: 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 Mcp Afip. Nothing to install.

What risk level is upload_certificate? +

upload_certificate is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit upload_certificate? +

Yes. Add a rate_limit block to the upload_certificate 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.

How do I block upload_certificate completely? +

Set action: deny in the PolicyLayer policy for upload_certificate. 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.

What MCP server provides upload_certificate? +

upload_certificate is provided by the Mcp Afip MCP server (codespar/mcp-dev-latam). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Afip tool call.

Start from Mcp Afip, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →