vault_login · Vault MCP: Risk & Policy

WHAT IT DOES

What vault_login does on Vault MCP

AI agents invoke vault_login to trigger actions in Vault MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why vault_login needs a policy

The tool performs an active browser automation action (filling and submitting a login form) using Chrome DevTools Protocol. This constitutes executing an external operation with real-world side effects (establishing an authenticated session on a third-party website).

From the tool's definition 'Log into a website using stored credentials' and 'Vault fills the login form via Chrome DevTools Protocol' — this triggers an external browser action (form submission/login) via CDP.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vault_login Rate-limited

vault_login stays usable, but rate-capped — a runaway agent can't fire it dozens of times 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_login": {
      "limits": [
        {
          "counter": "vault_login_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about vault_login

What does the vault_login tool do? +

Log into a website using stored credentials. The bot never sees the password — Vault fills the login form via Chrome DevTools Protocol. It is categorised as a Execute tool in the Vault MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on vault_login? +

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

What risk level is vault_login? +

vault_login is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit vault_login? +

Yes. Add a rate_limit block to the vault_login 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_login completely? +

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

vault_login is provided by the Vault MCP server (zerocreds-com/zerocreds-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.