Synap MCP server

Synap by Linkrra as a Model Context Protocol server: open models behind one OpenAI-compatible API. Your agent can list the models we serve, read their prices and limits, estimate the cost of a job before running it, and run a chat completion.

There is one server, hosted at https://pool.linkrra.com/mcp (Streamable HTTP). It is the server behind com.linkrra/synap in the official MCP registry.

This repository has two parts:

• routes.js is the deployed router itself, byte for byte.

• bin/synap-mcp.js is the stdio transport (npx synap-mcp) for MCP hosts that launch a local command. It sends every message to the hosted server unchanged, so it always exposes the same tools as the hosted server.

Tools

Model ids are the ones synap_list_models returns. Pass synap-v1 and Synap picks the cheapest model that can do the job.

Related MCP server: yuntu-mcp-server

Connect

Hosted (Streamable HTTP), no install needed

{
  "mcpServers": {
    "synap": {
      "type": "http",
      "url": "https://pool.linkrra.com/mcp",
      "headers": { "Authorization": "Bearer YOUR_SYNAP_API_KEY" }
    }
  }
}

Local stdio (Claude Desktop, Cursor, Cline, Windsurf, Zed)

{
  "mcpServers": {
    "synap": {
      "command": "npx",
      "args": ["-y", "synap-mcp"],
      "env": { "SYNAP_API_KEY": "YOUR_SYNAP_API_KEY" }
    }
  }
}

Without a key, the three free tools still work. synap_chat_completion returns an error and nothing is charged.

Paying

• API key (MCP and REST). Top up a Synap account by card or crypto. Each call is billed per token against that balance. MCP always uses this method.

• x402, no account. An agent with a USDC wallet on Base can pay per call over plain HTTP at POST https://pool.linkrra.com/api/billing/x402/chat/completions. An unpaid request returns 402 with the payment terms. This route is part of the REST API, not an MCP tool.

Protocol

The hosted server speaks both MCP eras:

• 2026-07-28 (current): stateless. It implements server/discover and reads the per-request _meta protocol version. It checks that MCP-Protocol-Version, Mcp-Method and Mcp-Name match the request body. Results carry resultType, and list results also carry ttlMs and cacheScope.

• 2025-11-25, 2025-06-18, 2025-03-26, 2024-11-05: the initialize handshake.

The bridge works with both. For a legacy client, it remembers the version agreed during initialize. For a 2026-07-28 client, it copies the _meta version into the HTTP headers that the Streamable HTTP transport requires.

The API behind it

https://pool.linkrra.com/v1 is an OpenAI-compatible API. On every self-hosted model it supports tool calling (tools, tool_choice) and structured outputs (response_format json_object / json_schema). Requests can be streamed or not. Prompts and completions are not stored.

Auth

The server passes your key through and nothing else. The key travels in the standard Authorization: Bearer header, the same way it would on a direct call to /v1/chat/completions. routes.js forwards that header untouched. The server never reads, stores or creates a key.

Run the server standalone

npm install && npm start     # serves :8080/mcp

Develop

npm test     # offline: a local mock checks the bridge's headers for both protocol eras

The stdio bridge needs Node 18 or later and has no dependencies.

License

Apache-2.0