Signet MCP Tools — Claude Code MCP server: signed tool calls, offline
Signs an agent's tool calls and lets anyone verify them offline with a public key. Useful when you have to prove what the agent actually did.
claude mcp add signet-mcp-tools -- npx -y @signet-auth/mcp-toolsWhat Signet MCP Tools does
Over stdio the server hands the agent three kinds of tools: signing, verification, and content hashing. It is the MCP face of Signet, where each agent carries an Ed25519 identity. A signed receipt goes with every tool call. Change a field and the signature fails; delete or reorder entries and the SHA-256 chain fails.
No network, no API key, no login. Verification needs the public key alone, so you can hand a receipt to an auditor and they check it themselves instead of trusting the hosting platform or the log store. Keep ordinary logs for observability. Reach for this when you need evidence.
Node.js is the prerequisite, since the server starts through npx -y @signet-auth/mcp-tools. The repository ships under Apache-2.0, and the underlying libraries exist for Rust, Python and TypeScript. Signing happens on your machine, not on a vendor's.
What it helps with
- sign a single tool call and keep the receipt
- verify a signature offline from a public key
- hash content through an MCP tool
- spot a tampered field in an agent action log
- hand an auditor checkable proof of what ran
Example prompts for the agent
- Sign this tool call and show me the receipt
- Verify the signature in
receipt.jsonagainst the public key - Compute the SHA-256 of
payload.json
How to install Signet MCP Tools
Platform CLI
claude mcp add signet-mcp-tools -- npx -y @signet-auth/mcp-toolsPlatform CLI
codex mcp add signet-mcp-tools -- npx -y @signet-auth/mcp-toolsConfig file
{
"mcpServers": {
"signet-mcp-tools": {
"command": "npx",
"args": [
"-y",
"@signet-auth/mcp-tools"
]
}
}
}Config file
{
"servers": {
"signet-mcp-tools": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@signet-auth/mcp-tools"
]
}
}
}Platform CLI
gemini mcp add signet-mcp-tools npx -y @signet-auth/mcp-toolsStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Signet MCP Tools
How do I install Signet MCP Tools in Claude Code?
Run claude mcp add signet-mcp-tools -- npx -y @signet-auth/mcp-tools. That single command registers the server.
What does Signet MCP Tools do?
It exposes signing, signature verification and content hashing tools to the agent. Tool calls get signed receipts that can be checked later without a network.
What do I need to run it?
Node.js, because it launches via npx. Ed25519 signatures and the SHA-256 chain are computed locally, and verification needs no connection.
