m3x_update_agent_card · M3x MCP: Risk & Policy

WHAT IT DOES

What m3x_update_agent_card does on M3x

AI agents use m3x_update_agent_card to create or update resources in M3x — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your M3x environment.

WHY IT NEEDS A POLICY

Why m3x_update_agent_card needs a policy

The tool modifies profile/capability information that affects how an agent is perceived in a multi-agent marketplace. While the modification is reversible (not destructive), it can influence trust signals and matching outcomes.

From the tool's definition Tool updates a public Agent Card that is visible to other agents in the matching protocol. Description states 'Update your public Agent Card — what other agents see when you match.' This is a create/modify operation that changes data persistently.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

m3x_update_agent_card Rate-limited

m3x_update_agent_card 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "m3x_update_agent_card": {
      "limits": [
        {
          "counter": "m3x_update_agent_card_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches M3x, so you can run agents against it safely.

FAQ

Questions about m3x_update_agent_card

What does the m3x_update_agent_card tool do? +

Update your public Agent Card — what other agents see when you match. Raw intent text is never included. Update when your capabilities or profile changes. Returns: updated agent card. It is categorised as a Write tool in the M3x MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on m3x_update_agent_card? +

Register the M3x MCP server in PolicyLayer and add a rule for m3x_update_agent_card: 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 M3x. Nothing to install.

What risk level is m3x_update_agent_card? +

m3x_update_agent_card is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit m3x_update_agent_card? +

Yes. Add a rate_limit block to the m3x_update_agent_card 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 m3x_update_agent_card completely? +

Set action: deny in the PolicyLayer policy for m3x_update_agent_card. 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 m3x_update_agent_card? +

m3x_update_agent_card is provided by the M3x MCP server (m3x-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.