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.
This record as markdown: /tools/4quays-mcp/sign.md
What sign does on 4quays
AI agents call sign 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 |
|---|---|---|---|
content | string | Yes | The exact message text to sign |
audience | string | — | Optional audience binding (the intended recipient) |
expiresInSeconds | integer | — | Optional expiry, in seconds from now |
Parameters from the server's own tool schema.
Why sign is rated Low
Even though sign 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.
Risk signalsAccepts raw HTML/template content (content)
Attacks that exploit this kind of access
The rule that runs sign 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 sign, this is the rule to start with:
sign is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect 4quays, apply this rule, and every sign call is checked against it from then on.
Questions about 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. It is categorised as a Read tool in the 4quays MCP Server, which means it retrieves data without modifying state.
sign accepts 3 parameters: content, audience, expiresInSeconds. Required: content. The full parameter table on this page comes from the server's own tool schema.
Register the 4quays MCP server in PolicyLayer and add a rule for sign: 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.
sign is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the sign 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.
Set action: deny in the PolicyLayer policy for sign. 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.
sign 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.
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