solana_signMessage · Privy MCP Server MCP: Risk & Policy

WHAT IT DOES

What solana_signMessage does on Privy MCP Server

AI agents invoke solana_signMessage to trigger actions in Privy MCP Server. 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 solana_signMessage needs a policy

Signing a message with a cryptographic wallet key is an execution operation that produces a cryptographic signature. While signing a plain message doesn't directly move funds, it can be used to authorize actions, authenticate identities, or approve off-chain agreements—making it a significant operation.

From the tool's definition Sign a message with a Solana wallet

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

solana_signMessage Rate-limited

solana_signMessage 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": {
    "solana_signMessage": {
      "limits": [
        {
          "counter": "solana_signmessage_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 Privy MCP Server, so you can run agents against it safely.

FAQ

Questions about solana_signMessage

What does the solana_signMessage tool do? +

Sign a message with a Solana wallet. It is categorised as a Execute tool in the Privy MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on solana_signMessage? +

Register the Privy MCP Server MCP server in PolicyLayer and add a rule for solana_signMessage: 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 Privy MCP Server. Nothing to install.

What risk level is solana_signMessage? +

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

Can I rate-limit solana_signMessage? +

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

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

solana_signMessage is provided by the Privy MCP Server MCP server (privy-io/privy-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.