Initial release: Lua MCP server library

Zero-dependency MCP (Model Context Protocol) server in pure Lua.
Only requires luasocket. 2MB RSS vs Python FastMCP's 97MB.

- json.lua: pure Lua JSON encoder/decoder (~150 lines)
- lmcp.lua: MCP server with streamable-http transport (~230 lines)
- example_server.lua: shell/file tools demo

Implements MCP 2025-03-26: initialize, tools/list, tools/call,
notifications/initialized, ping. JSON-RPC 2.0. SSE support. CORS.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

example_server.lua

@@ -0,0 +1,73 @@
+#!/usr/bin/env lua
+-- Example lmcp server — shell tools
+-- Usage: lua example_server.lua [port]
+
+local dir = arg[0]:match('(.*/)')  or './'
+package.path = package.path .. ';' .. dir .. '?.lua'
+
+local lmcp = require('lmcp')
+
+local server = lmcp.new("example-tools", {
+    port = tonumber(arg[1]) or 8080,
+})
+
+server:tool("shell", "Execute a shell command", {
+    type = "object",
+    properties = {
+        command = { type = "string", description = "Shell command to execute" },
+        timeout = { type = "integer", description = "Timeout in seconds", default = 30 },
+    },
+    required = { "command" },
+}, function(args)
+    local handle = io.popen(args.command .. ' 2>&1', 'r')
+    if not handle then return "Error: could not execute command" end
+    local result = handle:read('*a')
+    handle:close()
+    return result ~= '' and result or '(no output)'
+end)
+
+server:tool("read_file", "Read a file", {
+    type = "object",
+    properties = {
+        path = { type = "string", description = "File path to read" },
+    },
+    required = { "path" },
+}, function(args)
+    local f = io.open(args.path, 'r')
+    if not f then return "Error: could not open " .. args.path end
+    local content = f:read('*a')
+    f:close()
+    return content
+end)
+
+server:tool("write_file", "Write content to a file", {
+    type = "object",
+    properties = {
+        path = { type = "string", description = "File path to write" },
+        content = { type = "string", description = "Content to write" },
+    },
+    required = { "path", "content" },
+}, function(args)
+    local f = io.open(args.path, 'w')
+    if not f then return "Error: could not open " .. args.path .. " for writing" end
+    f:write(args.content)
+    f:close()
+    return string.format("Written %d bytes to %s", #args.content, args.path)
+end)
+
+server:tool("list_dir", "List directory contents", {
+    type = "object",
+    properties = {
+        path = { type = "string", description = "Directory path", default = "." },
+    },
+}, function(args)
+    local path = args.path or '.'
+    local handle = io.popen('ls -1 ' .. path:gsub("'", "'\\''") .. ' 2>&1')
+    if not handle then return "Error: could not list " .. path end
+    local result = handle:read('*a')
+    handle:close()
+    return result
+end)
+
+io.stderr:write("Starting lmcp example server...\n")
+server:run()