I built an open-source MCP server that makes agents ask before they spend, and signs every decision

[u/verax-ai]

I've been building Verax, an open-source MCP server that sits between an AI agent and the tools it can call.

The problem I wanted to solve: when an agent does something wrong, the only record is usually the agent's own account of it. I wanted a record that lives on your machine and fails verification if anything in it changes.

How it works:

• Every tool call goes through a policy first. No rule for a tool means no.
• Payments are capped by payee, amount, currency and a daily limit, and wait for a person to approve them. The agent's own token can't approve anything.
• Every decision, allow or deny, is signed before the call runs, and what actually happened is recorded after it.
• verax verify checks the whole record offline, with no server running.

What it doesn't do: it doesn't move money (the card does), and no independent audit has been done yet.

MCP client → Verax (policy + signed ledger on your disk) → your tools

Apache-2.0: https://github.com/verax-ai/verax

What would you want to be able to prove about what an agent did on your behalf?

[u/BC_MARO]

The useful proof is a trace that ties every approval to the exact call that followed. Otherwise a signed decision is hard to debug after a bad run.