#!/usr/bin/env node
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { z } from 'zod';
import { handleTrimMessages } from './tools/trim.js';
import { handleSummarizeMessages } from './tools/summarize.js';
import {
TrimMessagesArgsSchema,
SummarizeMessagesArgsSchema,
SlimContextMessageSchema,
} from './types/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
import ru from 'zod/v4/locales/ru.js';
/**
* SlimContext MCP Server
*
* A Model Context Protocol (MCP) server that wraps the SlimContext library,
* providing AI chat history compression tools for MCP-compatible clients.
*
* The server provides tools that enable:
* - Token-based trimming compression (trim_messages)
* - AI-powered summarization compression (summarize_messages)
*/
// Export stateless flag for MCP
export const stateless = true;
async function createSlimContextMCPServer() {
try {
// Create MCP server
const server = new McpServer({
name: 'slimcontext-mcp-server',
title: 'SlimContext',
version: '1.0.0',
});
console.error('SlimContext MCP Server initialized with modern MCP SDK');
// Register trim_messages tool
server.tool(
'trim_messages',
'Compress chat message history using token-based trimming strategy. Removes oldest non-system messages when token count exceeds threshold while preserving system messages and recent context.',
{
messages: z
.array(SlimContextMessageSchema)
.min(1)
.describe('Array of chat messages to compress'),
maxModelTokens: z
.number()
.min(1)
.optional()
.default(8192)
.describe("Model's maximum token context window"),
thresholdPercent: z
.number()
.min(0)
.max(1)
.optional()
.default(0.7)
.describe('Percentage threshold to trigger compression (0-1)'),
minRecentMessages: z
.number()
.min(0)
.optional()
.default(2)
.describe('Minimum recent messages to always preserve'),
},
async ({
messages,
maxModelTokens,
thresholdPercent,
minRecentMessages,
}) => {
const args = {
messages,
maxModelTokens,
thresholdPercent,
minRecentMessages,
};
const result = await handleTrimMessages(args);
return result.content[0]?.text
? JSON.parse(result.content[0].text)
: { error: 'No content returned' };
}
);
// Register summarize_messages tool
server.tool(
'summarize_messages',
'Compress chat message history using AI-powered summarization strategy. Creates concise summaries of older messages while preserving system messages and recent context.',
{
messages: z
.array(SlimContextMessageSchema)
.min(1)
.describe('Array of chat messages to compress'),
maxModelTokens: z
.number()
.min(1)
.optional()
.default(8192)
.describe("Model's maximum token context window"),
thresholdPercent: z
.number()
.min(0)
.max(1)
.optional()
.default(0.7)
.describe('Percentage threshold to trigger compression (0-1)'),
minRecentMessages: z
.number()
.min(0)
.optional()
.default(4)
.describe('Minimum recent messages to always preserve'),
openaiApiKey: z
.string()
.optional()
.describe(
'OpenAI API key (can also be set via OPENAI_API_KEY environment variable)'
),
openaiModel: z
.string()
.optional()
.default('gpt-4o-mini')
.describe('OpenAI model to use for summarization'),
customPrompt: z
.string()
.optional()
.describe('Custom prompt for summarization (optional)'),
},
async ({
messages,
maxModelTokens,
thresholdPercent,
minRecentMessages,
openaiApiKey,
openaiModel,
customPrompt,
}) => {
const args = {
messages,
maxModelTokens,
thresholdPercent,
minRecentMessages,
openaiApiKey,
openaiModel,
customPrompt,
};
const result = await handleSummarizeMessages(args);
return result.content[0]?.text
? JSON.parse(result.content[0].text)
: { error: 'No content returned' };
}
);
// Graceful shutdown logic
function shutdown() {
console.log('Shutdown signal received');
process.exit(0);
}
process.on('SIGINT', shutdown);
process.on('SIGTERM', shutdown);
process.on('exit', shutdown);
process.on('uncaughtException', (err) => {
console.error('Uncaught Exception:', err);
});
console.error('SlimContext MCP Server tools registered successfully');
// const transport = new StdioServerTransport();
// await server.connect(transport);
return server;
} catch (error) {
console.error(
`Server initialization error: ${error instanceof Error ? error.message : String(error)}`
);
throw error;
}
}
async function main() {
const transport = new StdioServerTransport();
const server = await createSlimContextMCPServer();
await server.connect(transport);
console.error('SlimContext MCP Server running on stdio');
}
main().catch((error) => {
console.error('Fatal error in main():', error);
process.exit(1);
});
