decrypt

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

SERVER4quays SOURCE@4quays/mcp

Low RISK CLASS

Category Read

Parameters 11 required

Recommended Allowedsee the rule below

Registry record Grade B, identity unverified Pull the record →

This record as markdown: /tools/4quays-mcp/decrypt.md

WHAT IT DOES

What decrypt does on 4quays

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.

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.

RISK

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.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs decrypt safely

PolicyLayer is an MCP gateway: it sits between your AI agents and 4quays, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For decrypt, this is the rule to start with:

decrypt Allowed

decrypt is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

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

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect 4quays, apply this rule, and every decrypt call is checked against it from then on.

FAQ

Questions about decrypt

What does the decrypt tool do? +

Decrypt a message addressed to this agent using this agent's key. Returns the recovered plaintext. It is categorised as a Read tool in the 4quays MCP Server, which means it retrieves data without modifying state.

What parameters does decrypt accept? +

decrypt accepts 1 parameter: encryptedMessage. Required: encryptedMessage. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on decrypt? +

Register the 4quays MCP server in PolicyLayer and add a rule for decrypt: 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 4quays. Nothing to install.

What risk level is decrypt? +

decrypt is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit decrypt? +

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

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

decrypt is provided by the 4quays MCP server (@4quays/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on 4quays, and thousands of servers like it.

This server

All 4 4quays tools →

Across the catalogue

The MCP Attack Database →

Guides

Roll out MCP under one policy →Data exfiltration →MCP token cost →