Send Approval Gate MCP: Plan, Approve, Send, Verify

An MCP server that makes an AI agent plan, present an exact hash-bound approval, send once and verify, and records every step.

Developer · $29 Commercial · $99

Polar is the main checkout. Paddle is the alternative, for card or PayPal: Developer $29 · Commercial $99

One-time purchase.

What it is

Send Approval Gate MCP is a Node.js 22+ MCP server (stdio) with six tools: status, account, contacts, plan-send, send and verify-send. The approval binds plan ID, account, recipient, message SHA-256, backend and environment hash, so any change needs a new approval. Duplicate sends are blocked, an uncertain result becomes result_unknown and is never retried, and every step goes to a local ledger with crash recovery. You attach your own channel through a small backend plugin contract; a mock backend and example plugin are included. 47 tests, no npm dependencies. It keeps a cooperative agent's sends exact, single and auditable; it is not a security boundary against an agent you do not trust.

Quick start

node --test test/*.test.mjs
node src/cli.mjs --backend mock mcp
add it to your MCP client config

Compared with

Tool	Type	Notes
Hand-written confirm prompt	Ask the agent to confirm	No hash binding, no ledger, retries can double-send
Generic HITL frameworks	Approval steps inside an agent framework	Tied to one framework; not an MCP server
Send Approval Gate MCP	MCP server, source included	$29 one-time; hash-bound approval, single send, result_unknown, ledger

FAQ

How do I stop an AI agent from sending a message twice?

Route sends through plan-send and send. A plan can be sent once; a timeout or adapter failure is recorded as result_unknown and never retried automatically.

Does it include a Slack, email or messenger backend?

No. You write a small plugin with status, account, contacts, send and verifySend for your own channel. A mock backend and an example plugin are included.

Is it a security boundary?

No. The approval is a value passed to send, so an agent that can call every tool can build one. For human-only approval, create the approval and call send from a channel the agent cannot reach.

What do I need?

Node.js 22 or later and an MCP client that speaks stdio. No npm dependencies.

Is it a subscription?

No. One-time purchase, full source included.