# vantic

A signed mandate caps what an agent may pay and who it may pay, and the check runs before money moves. Useful when your agent calls payment APIs.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI
- Author: vanticlabs
- License: Apache-2.0 · policy=link-only · description only; the file stays with the author
- Source: https://github.com/vanticlabs/vantic
- Updated: 2026-07-31
- HTML: https://affpapa.org/en/nevibecode/mcp/vantic

## What it does

Vantic hands your agent a signed mandate: a per-transaction cap, a rolling budget, allowed actions and a counterparty allowlist. The guard sits outside the model and fires before the money-moving code, so a fully compromised agent still cannot spend out of scope. Every permitted action leaves a signed, hash-chained receipt you can verify offline and use as evidence if a charge is disputed.

There are two ways in. The `@vantic/sdk` library goes into your code — `generateKeyPair`, `issueMandate`, `AgentWallet` — and an existing payment tool can be gated with `wrapMcpTool`, where a blocked call comes back to the model as a tool error and the real charge never fires. Or run the MCP server with `npx vantic-mcp`, which exposes stateless verification tools to the host: `mandate_authorize`, `mandate_verify_chain`, `mandate_verify_credential`, `mandate_resolve_did`. No private keys on the server side.

Identity uses W3C `did:key` and `did:web`, and the owner-to-agent link is a Verifiable Credential. There are no dependencies beyond Node's built-in crypto: Ed25519 and SHA-256. This is v0.1. The code is described as production-quality, but it has not been audited and the wire format is not frozen — for real payments, read `ROADMAP.md` and the threat model in `spec/SPEC.md` first.

## Requirements
- Needs: Node.js (commands run via npx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add vantic -- npx -y @vantic/sdk
```

### Codex

**Platform CLI**
```bash
codex mcp add vantic -- npx -y @vantic/sdk
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "vantic": {
            "command": "npx",
            "args": [
                "-y",
                "@vantic/sdk"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "vantic": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@vantic/sdk"
            ]
        }
    }
}
```

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add vantic npx -y @vantic/sdk
```

## When to use it
- cap an agent's spend per transaction and per week
- keep an agent from paying counterparties you never approved
- block a payment planted through a prompt injection
- keep a signed action log for a disputed charge
- gate a payment tool you already have without restructuring it

## Example prompts
- Issue the agent a mandate for purchases up to $200 each, limited to `etsy.com`
- Wrap `purchaseTool` with `wrapMcpTool` so a blocked call returns as a tool error
- Verify the receipt chain for the agent's latest mandate

## Similar
- [Vaara](https://affpapa.org/en/nevibecode/mcp/vaara.md) — MCP server · ★ 15
- [scopeblind-mcp](https://affpapa.org/en/nevibecode/mcp/scopeblind-mcp.md) — MCP server · ★ 11
- [Agent Wormhole](https://affpapa.org/en/nevibecode/mcp/agent-wormhole.md) — MCP server · ★ 5
- [TollWarden](https://affpapa.org/en/nevibecode/mcp/tollwarden.md) — MCP server · ★ 2
- [payment-pci-security](https://affpapa.org/en/nevibecode/skills/payment-pci-security.md) — skill · 1000 installs
- [stripe](https://affpapa.org/en/nevibecode/skills/stripe.md) — skill · 704 installs

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md