# 4quays MCP server

Agent View of the PolicyLayer registry record for 4quays: identity, probed posture, risk grade, and all 4 tools classified. HTML page: https://policylayer.com/tools/4quays-mcp

## Facts

- Server id: `@4quays/mcp`
- Install: `npx -y @4quays/mcp`
- Homepage: https://www.npmjs.com/package/@4quays/mcp
- Registry record: grade B, identity unverified
- Lifecycle: active
- Rate-limited: no
- Tools: 4 (4 with introspected schema)
- Tool categories present: Read
- Context-window cost: 491 tokens per request — https://policylayer.com/token-cost/4quays-mcp
- Tags: 4quays mcp
- Record last modified: 2026-09-10T18:53:54.511Z

## Tools (4)

| Tool | Category | Risk | Record |
| --- | --- | --- | --- |
| `decrypt` | Read | Low | https://policylayer.com/tools/4quays-mcp/decrypt.md |
| `encrypt_for` | Read | Low | https://policylayer.com/tools/4quays-mcp/encrypt-for.md |
| `sign` | Read | Low | https://policylayer.com/tools/4quays-mcp/sign.md |
| `verify` | Read | Low | https://policylayer.com/tools/4quays-mcp/verify.md |

## Tool descriptions

- `decrypt` — Decrypt a message addressed to this agent using this agent's key. Returns the recovered plaintext.
- `encrypt_for` — Encrypt a message to another agent using its public key. No API key required — anyone can encrypt to an agent. Returns a 4QUAYS ENCRYPTED MESSAGE block.
- `sign` — Sign a message with this agent's key. Returns a portable 4QUAYS signed block (or a verify URL) to attach to your message so another party can confirm you sent it.
- `verify` — Verify a 4QUAYS signed message. No API key required. Returns the verified content plus whether the signature is valid and the signer is active — trust the message only when both hold.

## 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 · Recommended policies for every tool: https://policylayer.com/policies/4quays-mcp