@three-ws/brain-mcp

Any model, one interface — discover LLM providers and run chat completions through the three.ws multi-provider router, from any AI agent.

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A Model Context Protocol server that gives any AI assistant the three.ws multi-provider LLM router over stdio. Discover which models are available — Claude, the GPT-5.6 family, o3, Grok, Qwen, DeepSeek, NVIDIA Nemotron, IBM Granite, and more — and run a chat completion through whichever one fits, without wiring each vendor SDK yourself.

The router fronts every provider behind one endpoint and transparently falls back across mirrors and free tiers if the chosen model is briefly down. The free open-weight tiers (GPT-OSS 120B, NVIDIA NIM models) work with no key; the paid first-party flagships unlock with a three.ws API key.

Install

npm install @three-ws/brain-mcp

Or run with npx (no install):

npx @three-ws/brain-mcp

Quick start

Claude Code, one line:

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

To unlock the paid flagships, pass your three.ws API key:

claude mcp add brain -e THREE_WS_API_KEY=sk_live_… -- npx -y @three-ws/brain-mcp

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

{
	"mcpServers": {
		"brain": {
			"command": "npx",
			"args": ["-y", "@three-ws/brain-mcp"],
			"env": { "THREE_WS_API_KEY": "sk_live_…" }
		}
	}
}

Inspect the surface with the MCP Inspector:

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

Tools

Tool	Type	What it does
list_providers	read-only	List every LLM the router can reach — key, network, tier, max output, live availability, and whether it needs auth.
chat	read-only	Run a chat completion through the chosen provider; returns the full reply, the route taken, token usage, and timing.

Both tools read live data — the provider set and completions vary between calls, so neither is idempotent. chat does not mutate any platform state, so it is annotated read-only.

Input parameters

list_providers — no parameters.

chat — messages (required: 1–100 turns of { role: "user" | "assistant", content }, content ≤ 16,000 chars), provider (provider key from list_providers, default gpt-oss-120b), system (optional system prompt, ≤ 8,000 chars), maxTokens (optional, 64–16384, default 4096, clamped to the model's ceiling).

Example

Both responses below are shape illustrations — the live provider set and generations will differ.

// list_providers (example response)
> {}
{
  "ok": true,
  "count": 34,
  "available": 33,
  "default_provider": "gpt-oss-120b",
  "providers": [
    { "key": "gpt-oss-120b", "label": "GPT-OSS 120B", "network": "OpenAI · OpenRouter", "tier": "balanced", "maxOutput": 8192, "description": "Open-weight 120B from OpenAI. Fast, capable, free tier. Platform default.", "available": true, "requiresAuth": false },
    { "key": "claude-sonnet-5", "label": "Claude Sonnet 5", "network": "Anthropic", "tier": "balanced", "maxOutput": 16384, "description": "Near-Opus quality on coding and agentic work at Sonnet cost. Best for most tasks.", "available": true, "requiresAuth": true },
    { "key": "deepseek-r1", "label": "DeepSeek R1", "network": "DeepSeek", "tier": "reasoning", "maxOutput": 8192, "description": "Open reasoning model. Strong at math and code.", "available": true, "requiresAuth": true }
    /* … */
  ]
}

// chat (example response)
> {
    "provider": "claude-sonnet-5",
    "system": "You are terse.",
    "messages": [{ "role": "user", "content": "Name three Solana RPC methods." }]
  }
{
  "ok": true,
  "provider": "claude-sonnet-5",
  "model": "Claude Sonnet 5",
  "network": "Anthropic",
  "tier": "balanced",
  "routed_via": null,
  "content": "getBalance, getAccountInfo, getSignaturesForAddress.",
  "usage": { "input_tokens": 24, "output_tokens": 14, "total_tokens": 38 },
  "timing_ms": { "first_token": 412, "total": 980 }
}

routed_via is null when the requested provider answered directly; otherwise it names the mirror or free-tier route the router fell back to (so you always get an answer even if the first choice is briefly down).

Model availability is dynamic. Always call list_providers first rather than hardcoding a key. The current Claude ids are claude-fable-5, claude-opus-5, claude-sonnet-5, claude-opus-4-7, claude-sonnet-4-6, and claude-haiku-4-5, but the live list is the source of truth.

Authentication

Model class	Needs a key?
Free open-weight tiers (GPT-OSS 120B, and the NVIDIA NIM set: Nemotron 3 Super / Nemotron Super 49B / Nemotron Nano / DeepSeek V4 / Kimi K2 / Llama 4 Maverick / MiniMax M2)	No
Paid first-party flagships (Claude, GPT-5.6, o3, Qwen Plus, DeepSeek, …)	Yes — set THREE_WS_API_KEY

Create an API key at three.ws/dashboard/developers. Without it, paid models return a sign-in error and list_providers flags them with requiresAuth: true.

Requirements

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

Environment variables

Variable	Required	Default	Purpose
THREE_WS_BASE	no	https://three.ws	API base URL (override to self-host or target a preview).
THREE_WS_API_KEY	no	—	Bearer credential that unlocks the paid first-party flagships.
THREE_WS_TIMEOUT_MS	no	120000	Per-request timeout (completions stream server-side).

Errors

A failed tool call returns an MCP error result (isError: true) whose text is a single JSON object — { "ok": false, "error": "<code>", "message": "…" }, plus status and detail on upstream rejections:

error	Meaning	Recovery
upstream_error	The router rejected the request — status carries the real HTTP code: 400 (bad arguments or an unknown provider key), 401 (paid model without a valid THREE_WS_API_KEY), 429 (rate-limited), 502 (the model's stream failed before producing output).	Act on status; for 401 set a key, for an unknown key re-run list_providers.
timeout	No complete response within THREE_WS_TIMEOUT_MS. Long flagship generations can be slow — the default 120 s matches the router's own ceiling.	Retry, lower maxTokens, or pick a fast-tier provider.
network_error	The request never reached the router (DNS, offline, TLS).	Check connectivity / THREE_WS_BASE.
bad_config	THREE_WS_TIMEOUT_MS is not a positive number (thrown at startup).	Fix the env var.

If the requested provider fails mid-flight the router transparently falls back to a mirror or free tier and the reply's routed_via names the route taken — you only see an error when every route is exhausted.

Links

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

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