Vantic

What vantic MCP server does

The vantic MCP server provides a verification layer for agents that can move money. Its SDK lets an owner sign a mandate for an agent, defining an overall budget, a rolling budget period, a maximum transaction amount, permitted action types, approved counterparties, an expiry time, and revocation information. A payment is evaluated against those rules before the payment executor runs.

The package can also produce signed receipts for permitted actions. Receipts are linked into a hash chain and associate each result with the mandate that authorized it. They can be checked offline and used as an audit record or evidence in a payment dispute.

How it works

An owner and an agent each use an Ed25519 key pair. The owner issues a signed mandate for the agent, and an AgentWallet uses the agent's private key to authorize spending attempts. The wallet checks the proposed action deterministically. A rejected action raises a guard violation, so the wrapped payment function is not called.

Existing payment tools can be protected with wrapMcpTool. The wrapper maps a tool's arguments to a spending action and returns a tool error when the action is outside the mandate. This approach supports MCP, LangChain, function-calling, and raw tool-calling agents without requiring the underlying payment operation to be rewritten.

Identity can use bare keys or W3C did:key identifiers. The project also supports offline DID resolution, publishing the same key as did:web, and owner-to-agent relationships represented as W3C Verifiable Credentials.

Setup and configuration

Install the SDK from npm with npm install @vantic/sdk. Generate owner and agent keys, issue a mandate with the required scope, and construct an AgentWallet with the mandate and agent private key. Payment calls then run inside the wallet's executor callback.

For MCP verification, run npm run mcp; the README also documents npx vantic-mcp for the published command. The MCP process is stateless and is intended to be run by an MCP host. It does not receive private keys.

Tools and capabilities

The vantic MCP server exposes these verification tools:

• mandate_authorize checks whether an action is authorized by a mandate.
• mandate_verify_chain validates a receipt chain.
• mandate_verify_credential verifies the sponsor credential connecting an owner and agent.
• mandate_resolve_did resolves supported DID identifiers.

The SDK uses Node's built-in cryptography, including Ed25519 signatures, SHA-256 hashing, canonical JSON, and W3C DID and credential formats. Supported spending examples include purchases, subscriptions, transfers, payouts, refunds, and pay-per-use actions, provided they are represented within the mandate's allowed scope.

Limitations and notes

The project identifies itself as v0.1. Its wire format is not frozen, and the implementation has not undergone an audit. The MCP tools provide verification rather than payment execution, and the MCP process does not store private keys. Deployments should therefore keep signing keys and payment operations under the caller's control. The repository is licensed under Apache-2.0.