update_call

THE RISK

Medium Risk

Why update_call needs a policy

This tool modifies existing data (an in-progress call's status) but does not delete or destroy information. It appears to be a Write operation as changes are reversible. Severity is medium because modifying call records in a tax authority system could affect audit trails or dispute resolution processes, but the impact is limited to metadata updates rather than core financial transactions or data deletion.

From the tool's definition Tool name 'update_call' and description 'Modify an in-progress call' indicate reversible modification of call state/status data.

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

POLICY

How to control update_call

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 update_call:

policy.json

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

update_call 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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All 1300 Mcp Afip tools →

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 update_call

What does the update_call tool do? +

Modify an in-progress call. Set Status=. 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 update_call? +

Register the Mcp Afip MCP server in PolicyLayer and add a rule for update_call: 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 update_call? +

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

Can I rate-limit update_call? +

Yes. Add a rate_limit block to the update_call 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 update_call completely? +

Set action: deny in the PolicyLayer policy for update_call. 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 update_call? +

update_call 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 →