three.ws Tutor

[three.ws]

@three-ws/tutor-mcp

Manage a Pay-As-You-Learn tutoring session from any AI agent — read its itemized running tab and close it for an attested invoice.

[npm] [license] [node] [MCP Registry] [three.ws]

A Model Context Protocol server that exposes the three.ws Pay-As-You-Learn tutor ledger over stdio. Read a tutoring session's itemized tab — one line item per answered question, with per-item cost and a running total — and close the session to seal an attested invoice.

The tutor bills per answered question; this server's tools are free. Viewing the running tab and closing the session never charge the learner — a learner must never pay to see what they owe or to end the session. Sessions are addressed by an opaque sessionId, so no API key and no signer are required — point THREE_WS_BASE at a deployment and go.

Install

npm install @three-ws/tutor-mcp

Or run with npx (no install):

npx @three-ws/tutor-mcp

Quick start

Claude Code, one line:

claude mcp add tutor -- npx -y @three-ws/tutor-mcp

Claude Desktop / Cursor (claude_desktop_config.json or mcp.json):

{	"mcpServers": {		"tutor": {			"command": "npx",			"args": ["-y", "@three-ws/tutor-mcp"]		}	}}

Inspect the surface with the MCP Inspector:

npx -y @modelcontextprotocol/inspector npx @three-ws/tutor-mcp

Tools

Both tools are free and move no funds: the per-question answers are the paid action (handled elsewhere). load_session reads live data — the tab grows as questions are billed, so it is not idempotent. close_session mutates state (open → closed) but is itself idempotent: re-closing returns the same itemized total.

Input parameters

load_session — sessionId (required, ≤100 chars).

close_session — sessionId (required, ≤100 chars).

Example

// load_session> { "sessionId": "learn-abc123" }{  "ok": true,  "sessionId": "learn-abc123",  "status": "open",  "createdAt": "2026-06-24T03:40:00.000Z",  "questionCount": 2,  "lineItems": [    { "n": 1, "question": "What is a Solana PDA?", "level": "intro", "outputTokens": 180, "costAtomics": 10000, "costUsd": "0.010000", "at": "2026-06-24T03:41:00.000Z" },    { "n": 2, "question": "How do CPIs work?", "level": "intro", "outputTokens": 220, "costAtomics": 10000, "costUsd": "0.010000", "at": "2026-06-24T03:42:00.000Z" }  ],  "totalAtomics": 20000,  "totalUsd": "0.020000"}

// close_session> { "sessionId": "learn-abc123" }{  "ok": true,  "sessionId": "learn-abc123",  "createdAt": "2026-06-24T03:40:00.000Z",  "closedAt": "2026-06-24T03:45:00.000Z",  "questionCount": 2,  "lineItems": [ /* same itemized line items */ ],  "totalAtomics": 20000,  "totalUsd": "0.020000",  "attestation": "sha256:…"}

A sessionId with no stored history returns an empty open session (questionCount: 0) rather than an error — an honest "nothing billed yet", not a failure.

Requirements

• Node.js >= 20.
• Network access to https://three.ws (or your own THREE_WS_BASE).

Environment variables

Links

• Homepage: https://three.ws
• Changelog: https://three.ws/changelog
• Issues: https://github.com/nirholas/three.ws/issues
• License: Apache-2.0, see LICENSE

_{Part of the three.ws SDK suite — 3D AI agents, on-chain identity, and agent payments.
Website · Changelog · GitHub}