A Lua SDK for OpenResty

[ufownl]

Pre-submission Checklist

• This post follows the MCP community guidelines

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I published a Lua SDK for OpenResty, which is developed according to the 2025-03-26 specification.

Note

lua-resty-mcp is now compatible with the latest (2025-06-18) specification

• Transports
  • stdio
  • Streamable HTTP
  • WebSocket (non-specification)
• Protocols
  • Lifecycle
  • Prompts
  • Resources
  • Tools
  • Roots
  • Sampling
  • Elicitation
  • Utilities
    • Pagination
    • Progress
    • Cancellation
    • Completion
    • Logging
    • Ping

Tip

Now, servers using the Streamable HTTP transport can choose a Redis-based message bus for distributed horizontal scaling!

The following examples demonstrate creating an MCP server using the stdio or Streamable HTTP transport.

stdio transport:

-- Import lua-resty-mcp module
local mcp = require("resty.mcp")
-- Create an MCP server session with stdio transport
local server = assert(mcp.server(mcp.transport.stdio, {}))
-- Register a tool
assert(server:register(mcp.tool("echo", function(args)
  return "Tool echo: "..args.message
end, {
  description = "Echo a message as a tool",
  input_schema = {
    type = "object",
    properties = {
      message = {type = "string"}
    },
    required = {"message"}
  }
})))
-- Launch the server session
server:run()

Streamable HTTP transport:

worker_processes auto;

events {
}

http {
  lua_shared_dict mcp_message_bus 64m;

  server {
    listen 80;

    location = /mcp {
      content_by_lua_block {
        -- Define an MCP endpoint
        require("resty.mcp").transport.streamable_http.endpoint(function(mcp, server)
          -- Register a tool
          assert(server:register(mcp.tool("echo", function(args)
            return "Tool echo: "..args.message
          end, {
            description = "Echo a message as a tool",
            input_schema = {
              type = "object",
              properties = {
                message = {type = "string"}
              },
              required = {"message"}
            }
          })))
          -- Launch the server session
          server:run()
        end)
      }
    }
  }
}

Relevant Links

GitHub repository: https://github.com/ufownl/lua-resty-mcp