log-collector

MCP server for collecting and analyzing CLI/web server error logs.

A lightweight server that watches log files and directories, parses common error patterns from CLI tools and web servers, and provides structured querying and analysis — all through the Model Context Protocol (MCP).

Features

• File & directory watching — watch single log files or entire directories with glob patterns

• Multi-source support — simultaneously monitor multiple log sources

• Smart parsing — automatically detects and parses errors from:

  • Vite / Rollup build errors

  • JavaScript/TypeScript stack traces (Error, TypeError, ReferenceError, etc.)

  • esbuild / Vite ×-prefixed build errors

  • npm ERR! output

  • Build failures ("Build failed", "Failed to compile")

  • Warnings (WARN, ⚠, [warn])

  • HTTP server errors (4xx client errors, 5xx server errors)

  • Build success / ready messages

• Filtered queries — retrieve logs by source, level, time range, and limit

• Auto-analysis — get summary statistics and top error counts grouped by normalized message

• In-memory ring buffer — retains up to 10,000 entries per session

Related MCP server: log-mcp

Quick Start

Prerequisites

• Node.js >= 20

• npm

Installation

# Install globally
npm install --global @bonsai/log-collector

# Or run with npx
npx @bonsai/log-collector

Build from source

git clone https://github.com/bonsai/log-collector.git
cd log-collector
npm install
npm run build
npm start

Usage

log-collector is an MCP server that communicates over stdio. It is designed to be used as a tool provider for MCP-compatible clients (e.g., Claude Desktop, Claude Code).

MCP Tools

Tool Parameters

watch_start

get_errors

analyze

Returns: total entries, error/warning/info counts, top 10 most frequent errors, and list of active sources.

Architecture

┌─────────────┐     ┌──────────┐     ┌──────────┐
│  chokidar   │────▶│Collector │────▶│ Storage  │
│ (FS watcher)│     │(readTail)│     │(10k ring)│
└─────────────┘     └──────────┘     └──────────┘
                            │
                     ┌──────▼──────┐
                     │   Parser    │
                     │ (pattern    │
                     │  matching)  │
                     └─────────────┘

┌─────────────┐
│  MCP Server │ (stdio transport)
│  (index.ts) │
└─────────────┘
     │
     ▼
  MCP Client
(Claude Desktop,
 Claude Code, etc.)

Components

• index.ts — MCP server entry point; registers tools and handles requests

• collector.ts — File watcher manager using chokidar; reads tail of changed files

• parser.ts — Pattern-based log parser; recognizes Vite, npm, HTTP, and generic error formats; also provides analyze() for summary aggregation

• storage.ts — In-memory ring buffer with filtered query support

Development

# Install dependencies
npm install

# Build
npm run build

# Run locally
npm start

# Watch mode (auto-restart on changes)
npx tsx src/index.ts

Adding new log patterns

Edit src/parser.ts and add a new entry to the patterns array:

{
  name: "my-tool-error",
  test: (line) => {
    const m = line.match(/^MY_ERROR:\s+(.+)/);
    if (m) return { level: "error", message: m[1], detail: line };
    return null;
  },
},

Use Cases

• AI-assisted debugging — Feed your local dev server logs to Claude via MCP and ask it to diagnose errors

• CI log monitoring — Watch build logs during development to catch failures early

• Web server log analysis — Point it at your Nginx/Apache access logs to get structured error summaries

• Multi-project log aggregation — Watch multiple project log directories simultaneously

License

MIT