# decrypt

Decrypt a message addressed to this agent using this agent's key. Returns the recovered plaintext.

Agent View of the PolicyLayer registry record for `decrypt`. HTML page: https://policylayer.com/tools/4quays-mcp/decrypt

## Facts

- Tool: `decrypt`
- Server: 4quays (`@4quays/mcp`) — https://policylayer.com/tools/4quays-mcp.md
- Install: `npx -y @4quays/mcp`
- Homepage: https://www.npmjs.com/package/@4quays/mcp
- Risk category: Read (Low risk)
- Registry record: grade B, identity unverified
- Server rate-limited: no
- Parameters: 1 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `encryptedMessage` | string | yes | A 4QUAYS ENCRYPTED MESSAGE block or a raw compact JWE |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "decrypt",
    "arguments": {
      "encryptedMessage": "<encryptedMessage>"
    }
  }
}
```

## Why decrypt is rated Low

Even though decrypt only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

## Use case

AI agents call decrypt to retrieve information from 4quays without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches 4quays:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "decrypt": {}
  }
}
```

## Other tools on 4quays (3)

- `encrypt_for` — Read — https://policylayer.com/tools/4quays-mcp/encrypt-for.md
- `sign` — Read — https://policylayer.com/tools/4quays-mcp/sign.md
- `verify` — Read — https://policylayer.com/tools/4quays-mcp/verify.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=4quays-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/4quays-mcp