web-researcher-mcp

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README

web-researcher-mcp

A production-grade MCP server that gives AI assistants the power to search the web, extract content, and conduct multi-source research.

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Why Web Researcher MCP?

AI assistants are only as good as the information they can access. web-researcher-mcp bridges the gap between LLMs and the live internet through the Model Context Protocol standard:

  • 8 specialized research tools in a single server
  • 4 pluggable search backends (Google, Brave, Serper, SearXNG)
  • Tiered content extraction -- markdown negotiation, HTML parsing, headless browser, document parsing
  • Search lenses for domain-focused research (programming, news, legal, medical, and more)
  • Single static binary (~20MB) with zero runtime dependencies
  • Enterprise-ready with OAuth 2.1, multi-tenancy, rate limiting, and audit logging

Works with Claude Code, Claude Desktop, Cursor, and any MCP-compatible client.

Tools

Tool Description
web_search General web search with optional search lenses for domain-focused results
scrape_page Extract content from any URL -- web pages, PDFs, DOCX, PPTX, YouTube transcripts
search_and_scrape Combined search + extraction pipeline with quality scoring and deduplication
image_search Search for images with size, type, color, and file format filters
news_search Search news sources with freshness controls and source filtering
academic_search Search academic papers via Scholar, arXiv, and PubMed
patent_search Search patent databases with CPC classification for prior art and IP research
sequential_search Multi-step research tracking with session state for iterative investigation

Quick Start

One-Line Install (Claude Code)

claude mcp add web-researcher -- go run github.com/zoharbabin/web-researcher-mcp/cmd/web-researcher-mcp@latest

Then set your API keys in ~/.claude/settings.json under the server's env block (see Connect to Your AI Assistant below).

Option 1: Download Binary

Download the latest release for your platform from Releases:

# macOS (Apple Silicon)
curl -L https://github.com/zoharbabin/web-researcher-mcp/releases/latest/download/web-researcher-mcp-darwin-arm64 -o web-researcher-mcp
chmod +x web-researcher-mcp

# macOS (Intel)
curl -L https://github.com/zoharbabin/web-researcher-mcp/releases/latest/download/web-researcher-mcp-darwin-amd64 -o web-researcher-mcp
chmod +x web-researcher-mcp

# Linux (x86_64)
curl -L https://github.com/zoharbabin/web-researcher-mcp/releases/latest/download/web-researcher-mcp-linux-amd64 -o web-researcher-mcp
chmod +x web-researcher-mcp

Option 2: Docker

docker run -e GOOGLE_CUSTOM_SEARCH_API_KEY=YOUR_KEY \
           -e GOOGLE_CUSTOM_SEARCH_ID=YOUR_CX \
           zoharbabin/web-researcher-mcp

Option 3: Build from Source

git clone https://github.com/zoharbabin/web-researcher-mcp.git
cd web-researcher-mcp
go build -o web-researcher-mcp ./cmd/web-researcher-mcp

Or install directly:

go install github.com/zoharbabin/web-researcher-mcp/cmd/web-researcher-mcp@latest

Connect to Your AI Assistant

Add this to your MCP client configuration (example for Claude Code ~/.claude/settings.json):

{
  "mcpServers": {
    "web-researcher": {
      "command": "/path/to/web-researcher-mcp",
      "env": {
        "GOOGLE_CUSTOM_SEARCH_API_KEY": "YOUR_GOOGLE_API_KEY",
        "GOOGLE_CUSTOM_SEARCH_ID": "YOUR_SEARCH_ENGINE_ID"
      }
    }
  }
}

Done. Your AI assistant now has access to all 8 research tools.

Configuration

Required

Variable Description How to Get
GOOGLE_CUSTOM_SEARCH_API_KEY Google API key Google Cloud Console
GOOGLE_CUSTOM_SEARCH_ID Programmable Search Engine ID PSE Console

Search Provider

Variable Description Default
SEARCH_PROVIDER Backend: google, brave, serper, or searxng google
BRAVE_API_KEY Brave Search API key
SERPER_API_KEY Serper.dev API key
SEARXNG_URL SearXNG instance URL

HTTP Transport (Optional)

Variable Description Default
PORT Enable HTTP/SSE mode STDIO only
OAUTH_ISSUER_URL JWT issuer URL for token validation
OAUTH_AUDIENCE Expected JWT audience claim
All Environment Variables
Variable Description Default
GOOGLE_CUSTOM_SEARCH_API_KEY Google API key (required)
GOOGLE_CUSTOM_SEARCH_ID Search engine ID (required)
SEARCH_PROVIDER Search backend google
BRAVE_API_KEY Brave Search API key
SERPER_API_KEY Serper.dev API key
SEARXNG_URL SearXNG instance URL
PORT HTTP port (enables HTTP/SSE mode) STDIO
OAUTH_ISSUER_URL JWT issuer for auth
OAUTH_AUDIENCE Expected JWT audience
REDIS_URL Redis URL for shared cache/sessions in-memory
CACHE_TTL Cache time-to-live 1h
CACHE_ENCRYPTION_KEY Encryption key for cached content (64 hex chars)
RATE_LIMIT_RPM Requests per minute per client 60
LOG_LEVEL Logging level: debug, info, warn, error info
LOG_FORMAT Log format: json, text json
METRICS_PORT Prometheus metrics endpoint port disabled
MAX_CONCURRENT_SCRAPES Concurrent scrape limit 5
SCRAPE_TIMEOUT Per-scrape timeout 30s

Architecture

web-researcher-mcp/
├── cmd/web-researcher-mcp/     # Entry point (wiring only, ~50 lines)
├── internal/
│   ├── config/                 # Env-based strongly-typed configuration
│   ├── server/                 # MCP server lifecycle + signal handling
│   ├── tools/                  # Tool handlers (one file per tool)
│   ├── search/                 # Pluggable search providers + lens routing
│   ├── scraper/                # Tiered scraping pipeline
│   ├── documents/              # PDF, DOCX, PPTX parsing
│   ├── cache/                  # Hybrid cache (ristretto + disk + optional Redis)
│   ├── auth/                   # OAuth 2.1 middleware + JWKS
│   ├── session/                # Per-tenant session management
│   ├── content/                # Sanitize, dedup, truncate, quality score
│   ├── metrics/                # Prometheus metrics + per-tool stats
│   ├── ratelimit/              # Three-tier rate limiting
│   ├── circuit/                # Circuit breaker for external APIs
│   └── resources/              # MCP Resources + Prompts
├── lenses/                     # Search lens JSON files
└── docs/                       # Extended documentation
High-Level Architecture Diagram 
┌─────────────────────────────────────────────────────────────────┐
│                         MCP Protocol Layer                        │
│  ┌──────────────────┐              ┌─────────────────────────┐  │
│  │  STDIO Transport │              │  HTTP/SSE Transport     │  │
│  │  (zero-config)   │              │  (OAuth 2.1 + CORS)     │  │
│  └────────┬─────────┘              └──────────┬──────────────┘  │
│           └────────────────┬───────────────────┘                 │
│                    ┌───────▼───────┐                             │
│                    │  MCP Server   │                             │
│                    │  (go-sdk)     │                             │
│                    └───────┬───────┘                             │
└────────────────────────────┼─────────────────────────────────────┘
                             │
┌────────────────────────────┼─────────────────────────────────────┐
│                    Tool Dispatch Layer                             │
│  ┌─────────┐ ┌────────┐ ┌┴───────┐ ┌────────┐ ┌─────────────┐  │
│  │ Search  │ │ Scrape │ │Combined│ │Academic│ │ Sequential  │  │
│  │ Tools   │ │ Tool   │ │  Tool  │ │& Patent│ │  Research   │  │
│  └────┬────┘ └───┬────┘ └───┬────┘ └───┬────┘ └──────┬──────┘  │
└───────┼──────────┼───────────┼──────────┼─────────────┼──────────┘
        │          │           │          │             │
┌───────┼──────────┼───────────┼──────────┼─────────────┼──────────┐
│       │     Service Layer    │          │             │           │
│  ┌────▼────┐ ┌───▼────┐ ┌───▼───┐ ┌───▼────┐ ┌─────▼─────┐   │
│  │ Search  │ │Scraper │ │Quality│ │Citation│ │  Session   │   │
│  │Provider │ │Pipeline│ │Scorer │ │Extract │ │  Manager   │   │
│  └────┬────┘ └───┬────┘ └───────┘ └────────┘ └────────────┘   │
│       │          │                                               │
│  ┌────▼─────┐ ┌─▼──────────────────────────────────┐           │
│  │ Brave    │ │  Scraper Tiers                      │           │
│  │ Google   │ │  markdown > HTML > browser > docs   │           │
│  │ Serper   │ │  + YouTube transcripts              │           │
│  │ SearXNG  │ └─────────────────────────────────────┘           │
│  └──────────┘                                                    │
└──────────────────────────────────────────────────────────────────┘
        │          │
┌───────┼──────────┼──────────────────────────────────────────────┐
│       │   Infrastructure Layer                                    │
│  ┌────▼────┐ ┌───▼────┐ ┌─────────┐ ┌────────┐ ┌───────────┐  │
│  │  Cache  │ │  SSRF  │ │  Rate   │ │Metrics │ │   Audit   │  │
│  │(hybrid) │ │Protect │ │ Limiter │ │(Prom.) │ │   Logger  │  │
│  └─────────┘ └────────┘ └─────────┘ └────────┘ └───────────┘  │
│  ┌──────────────────┐  ┌──────────────────────────────────────┐ │
│  │  Circuit Breaker  │  │  Content Pipeline (sanitize, dedup,  │ │
│  │                   │  │  truncate, quality score)             │ │
│  └───────────────────┘  └──────────────────────────────────────┘ │
└──────────────────────────────────────────────────────────────────┘

Design Principles

  1. Zero global state -- all dependencies injected via constructors
  2. Interface-driven -- every external dependency behind an interface for testing and swapping
  3. Bounded concurrency -- explicit semaphores for external API calls
  4. Defense in depth -- SSRF protection, rate limiting, content sanitization at every layer
  5. Fail loud -- errors returned, never swallowed; validation at boundaries

Search Providers

The server supports four search backends. Google PSE is always used for lens-restricted and site-restricted queries (free, works indefinitely). The configured provider handles unrestricted whole-web searches.

Provider Cost per 1K Queries Whole-Web Images News Notes
Google PSE Free (100/day) to $5 Until 2027 Yes Yes Default; always used for lenses
Brave Search $5 (free tier available) Yes Yes Yes Recommended for whole-web
Serper.dev $0.30-$1 Yes Yes Yes Google-identical results
SearXNG Free (self-hosted) Yes Yes Yes Privacy-first, air-gapped deployments

Routing Logic

Request arrives
  |-- lens specified?     --> Google PSE (site-restricted, free forever)
  |-- site: param set?    --> Google PSE (site-restricted)
  `-- unrestricted?       --> Configured SEARCH_PROVIDER
Provider Setup Examples

Brave Search (recommended for whole-web):

export SEARCH_PROVIDER=brave
export BRAVE_API_KEY=BSAxxxxxxxxxx
export GOOGLE_CUSTOM_SEARCH_API_KEY=AIza...  # still needed for lenses
export GOOGLE_CUSTOM_SEARCH_ID=017...

SearXNG (self-hosted, privacy-first):

export SEARCH_PROVIDER=searxng
export SEARXNG_URL=http://localhost:8080
export GOOGLE_CUSTOM_SEARCH_API_KEY=AIza...
export GOOGLE_CUSTOM_SEARCH_ID=017...

Google PSE only (simplest setup):

export GOOGLE_CUSTOM_SEARCH_API_KEY=AIza...
export GOOGLE_CUSTOM_SEARCH_ID=017...
# SEARCH_PROVIDER defaults to "google"

Search Lenses

Search lenses are curated domain lists that focus search results on high-quality sources for specific topics. They route through Google PSE in site-restricted mode -- free and works indefinitely.

Built-in Lenses

Lens Focus Example Domains
programming Code docs, tutorials, Q&A stackoverflow.com, github.com, developer.mozilla.org
news Current events, journalism reuters.com, apnews.com, bbc.com, nytimes.com
tech Technology industry arstechnica.com, techcrunch.com, theverge.com
legal Law, cases, statutes law.cornell.edu, courtlistener.com, justia.com
medical Health, medicine nih.gov, mayoclinic.org, who.int, pubmed.ncbi.nlm.nih.gov
finance Markets, filings sec.gov, bloomberg.com, investopedia.com
science Research, papers nature.com, science.org, nasa.gov
government Policy, regulations *.gov, europa.eu, gov.uk, un.org

Usage Example

{
  "tool": "web_search",
  "arguments": {
    "query": "golang context best practices",
    "lens": "programming"
  }
}

This searches only stackoverflow.com, github.com, go.dev, developer.mozilla.org, and other curated programming sites.

Creating Custom Lenses

Add a JSON file to the lenses/ directory:

{
  "name": "my-custom-lens",
  "description": "Description of what this lens covers",
  "domains": [
    "example.com",
    "docs.example.org",
    "*.trusted-source.io"
  ],
  "cx": ""
}

Fields:

  • domains -- Up to 5,000 URL patterns per lens (Google PSE limit)
  • cx -- Optional dedicated PSE engine ID. If empty, site: operators are injected at query time (limited to ~10 domains per query)

Security

SSRF Protection

The server implements a custom DialContext that validates all resolved IPs before connecting:

  • Blocks all private/reserved IP ranges (127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, fc00::/7)
  • Blocks cloud metadata endpoints (169.254.169.254)
  • Validates against DNS rebinding by connecting only to the first resolved IP
  • Re-validates redirect targets at each hop
Authentication and Authorization

In HTTP mode, the server supports OAuth 2.1 with:

  • JWKS-based token validation with automatic key rotation
  • Per-tenant session isolation
  • Audience and issuer validation
  • Configurable claim extraction for multi-tenancy
Rate Limiting

Three-tier rate limiting protects both the server and upstream APIs:

  1. Per-client -- token bucket per authenticated session
  2. Per-provider -- prevents exceeding upstream API quotas
  3. Global -- server-wide backpressure valve
Content Safety
  • HTML sanitization via whitelist-based policy (bluemonday)
  • Paragraph-level deduplication across scraped results
  • Smart truncation at natural content breakpoints
  • Quality scoring to filter low-value results before returning to the LLM

For the full threat model and security architecture, see docs/SECURITY.md.

MCP Client Integration

Claude Code

Add to ~/.claude/settings.json:

{
  "mcpServers": {
    "web-researcher": {
      "command": "/path/to/web-researcher-mcp",
      "env": {
        "GOOGLE_CUSTOM_SEARCH_API_KEY": "AIza...",
        "GOOGLE_CUSTOM_SEARCH_ID": "017...",
        "SEARCH_PROVIDER": "brave",
        "BRAVE_API_KEY": "BSA..."
      }
    }
  }
}

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "web-researcher": {
      "command": "/path/to/web-researcher-mcp",
      "env": {
        "GOOGLE_CUSTOM_SEARCH_API_KEY": "AIza...",
        "GOOGLE_CUSTOM_SEARCH_ID": "017..."
      }
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "web-researcher": {
      "command": "/path/to/web-researcher-mcp",
      "env": {
        "GOOGLE_CUSTOM_SEARCH_API_KEY": "AIza...",
        "GOOGLE_CUSTOM_SEARCH_ID": "017..."
      }
    }
  }
}

HTTP/SSE Mode (Multi-Client, Teams)

For shared deployments serving multiple clients or web applications:

PORT=3000 \
OAUTH_ISSUER_URL=https://auth.example.com \
OAUTH_AUDIENCE=https://api.example.com \
./web-researcher-mcp

Connect any MCP client to http://localhost:3000/sse.

Docker Compose Example 
version: "3.8"
services:
  web-researcher:
    image: zoharbabin/web-researcher-mcp
    ports:
      - "3000:3000"
    environment:
      PORT: "3000"
      GOOGLE_CUSTOM_SEARCH_API_KEY: ${GOOGLE_CUSTOM_SEARCH_API_KEY}
      GOOGLE_CUSTOM_SEARCH_ID: ${GOOGLE_CUSTOM_SEARCH_ID}
      SEARCH_PROVIDER: brave
      BRAVE_API_KEY: ${BRAVE_API_KEY}
      REDIS_URL: redis://redis:6379
    depends_on:
      - redis

  redis:
    image: redis:7-alpine
    volumes:
      - redis-data:/data

volumes:
  redis-data:

Performance

Operation Expected Latency Notes
Search (cache hit) < 1ms Direct return from in-memory cache
Search (API call) 200-500ms Circuit-breaker protected
Scrape (markdown) 100-300ms Fastest tier via content negotiation
Scrape (HTML) 500-2000ms goquery-based extraction
Scrape (browser) 2-10s Headless Chrome, bounded to 3 concurrent
search_and_scrape 2-15s Parallel scrape with semaphore (max 5)

Development

# Build
go build -o web-researcher-mcp ./cmd/web-researcher-mcp

# Run all tests
go test ./...

# Tests with race detector
go test -race ./...

# E2E tests
go test -v ./tests/e2e/...

# Benchmarks
go test -bench=. ./tests/benchmark/

# Lint
golangci-lint run

# Security audit
govulncheck ./...

# Production build (static, stripped)
CGO_ENABLED=0 go build -ldflags="-s -w" -o web-researcher-mcp ./cmd/web-researcher-mcp

Contributing

Contributions are welcome. Please see docs/CONTRIBUTING.md for code style guidelines, development workflow, and how to submit pull requests.

Documentation

Document Description
ARCHITECTURE.md Full architecture, design decisions, technology stack
docs/TOOLS.md Detailed tool specifications and parameter schemas
docs/SECURITY.md Threat model, SSRF, authentication, content safety
docs/SEARCH_PROVIDERS.md Provider system, lenses, routing, migration plan
docs/DEPLOYMENT.md Build, Docker, Kubernetes, scaling
docs/TESTING.md Test strategy and patterns
docs/COMPLIANCE.md SOC2, GDPR, FedRAMP compliance
docs/GO_MODULE.md Every dependency with rationale

License

MIT

Built with Go and the Model Context Protocol

If this project helps your workflow, consider giving it a star.

Directories

Path Synopsis
cmd
web-researcher-mcp command
internal
audit
auth
cache
circuit
config
content
documents
metrics
ratelimit
resources
scraper
search
server
session
tools

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