@signet-auth/mcp

Client-side signing transport for MCP. Wrap an existing transport, inject _meta._signet into every tools/call, and collect receipts without changing server code.

Best for:

• MCP clients and agent runtimes you control
• Signing outbound tools/call requests without modifying the target server
• Collecting dispatch, compound, and bilateral receipts on the client side

Use another package if:

• You need verification before execution on the server: @signet-auth/mcp-server
• You want Signet as a standalone MCP server: @signet-auth/mcp-tools

Install

npm install @modelcontextprotocol/sdk @signet-auth/mcp @signet-auth/core

Usage

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
import { generateKeypair } from "@signet-auth/core";
import { SigningTransport } from "@signet-auth/mcp";

const { secretKey } = generateKeypair();
const inner = new StdioClientTransport({ command: "my-mcp-server" });
const transport = new SigningTransport(inner, secretKey, "my-agent", "team", {
  target: "mcp://my-mcp-server",
  trustedServerKeys: ["ed25519:..."],
  onDispatch: (receipt) => console.log("signed request", receipt.id),
  onBilateral: (receipt) => console.log("trusted bilateral", receipt.id),
});

const client = new Client({ name: "my-agent", version: "1.0.0" }, {});
await client.connect(transport);

await client.callTool({
  name: "echo",
  arguments: { message: "hello" },
});

Every outbound tools/call request gets a receipt injected into params._meta._signet.

Notes:

• trustedServerKeys is recommended whenever you expect bilateral receipts; without it, bilateral receipts are treated as integrity-only and do not trigger onBilateral by default.
• allowUntrustedBilateral: true is an explicit compatibility opt-in if you still want onBilateral for integrity-only receipts.

Related packages

• @signet-auth/core — lower-level signing and verification primitives
• @signet-auth/mcp-server — verify requests before execution on the server
• @signet-auth/mcp-tools — standalone MCP server exposing Signet tools
• Full documentation & all SDKs

If Signet is useful to you, star us on GitHub — it helps others discover the project.