vault_storeApiKey · Mailgent MCP Server MCP: Risk & Policy

WHAT IT DOES

What vault_storeApiKey does on Mailgent MCP Server

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

WHY IT NEEDS A POLICY

Why vault_storeApiKey needs a policy

This tool creates or updates a stored credential (API key) in a vault, which is a Write operation. The severity is high because misuse could allow an attacker to store malicious or unauthorized credentials, potentially enabling impersonation or unauthorized access to external services. The description is truncated ('Use just'), which slightly lowers confidence, but the core action of storing an API key is clear.

From the tool's definition 'Store an API_KEY credential' — the tool writes/persists an API key into a secure vault.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vault_storeApiKey Rate-limited

vault_storeApiKey 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": {
    "vault_storeApiKey": {
      "limits": [
        {
          "counter": "vault_storeapikey_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 Mailgent MCP Server, so you can run agents against it safely.

FAQ

Questions about vault_storeApiKey

What does the vault_storeApiKey tool do? +

Store an API_KEY credential. Use just. It is categorised as a Write tool in the Mailgent MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on vault_storeApiKey? +

Register the Mailgent MCP Server MCP server in PolicyLayer and add a rule for vault_storeApiKey: 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 Mailgent MCP Server. Nothing to install.

What risk level is vault_storeApiKey? +

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

Can I rate-limit vault_storeApiKey? +

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

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

vault_storeApiKey is provided by the Mailgent MCP Server MCP server (loomal-ai/loomal-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.