post_objects

THE RISK

Medium Risk

Why post_objects needs a policy

This tool creates or commits postal objects (PLP = Postagem de Lista de Mala Direta), which is a reversible write operation that generates official postal records. While it has business consequences, it does not delete data irreversibly or execute arbitrary commands. The 'creates' verb and context of posting shipments classify this as Write rather than Execute.

From the tool's definition Tool description states 'Close and post a list of pre-posted objects' and 'creates a PLP'. The action 'post' and 'creates' indicate modification/creation of shipping/postal records in the SIGEP (Brazilian postal) system.

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

POLICY

How to control post_objects

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 post_objects:

policy.json

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

post_objects 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 post_objects

What does the post_objects tool do? +

Close and post a list of pre-posted objects (fechar postagem SIGEP) — creates a PLP. 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 post_objects? +

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

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

Can I rate-limit post_objects? +

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

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

post_objects 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 →