AGENT HARNESSES

Most agent harnesses call the same frontier LLM backends (Anthropic Claude 3.7 Sonnet, OpenAI o3-mini/GPT-4o, DeepSeek R1). The actual differences lie in interface design, context management, MCP protocol support, permission controls, and local workflow integration.

Below is a detailed guide and configuration reference for the top AI agent harnesses.

1. Claude Code

A CLI-native autonomous agent from Anthropic that executes directly in your shell environment. It reads your entire project tree, runs terminal commands, and requests approval before executing critical filesystem or shell modifications.

• Type: Terminal CLI Agent
• Config Path: ~/.claude/ (Global) | CLAUDE.md (Project root) | .claude/mcp.json (MCP)
• Protocols: STDIO, HTTP, SSE
• Pricing: Anthropic API Key or Claude Pro/Team Plan
• Best For: Terminal-first developers who want autonomous multi-file refactoring and automated test/build loops.

### MCP Configuration Example Save to .claude/mcp.json:

{
  "mcpServers": {
    "context7": {
      "command": "npx",
      "args": ["-y", "@upstash/context7-mcp"]
    },
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "."]
    }
  }
}

2. Cursor

An AI-first VS Code fork engineered by Anysphere. Features native multi-file composer agents (Cmd+I), inline code edit generation (Cmd+K), instant codebase indexing, and full MCP server integration.

• Type: IDE (VS Code Fork)
• Config Path: ~/.cursor/mcp.json (Global MCP) | .cursor/rules/ (Project rules)
• Protocols: STDIO, SSE
• Pricing: Free Tier / Pro ($20/mo) / Enterprise
• Best For: Developers who want an out-of-the-box IDE experience with visual diff previews and instant codebase indexing.

### MCP Configuration Example Save to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "<your-token-here>"
      }
    }
  }
}

3. Windsurf

Created by Codeium, Windsurf is an AI-native IDE built around the Cascade agent framework. It blends autonomous multi-file edits with real-time context streaming and terminal action execution.

• Type: IDE (Codeium Fork)
• Config Path: ~/.codeium/windsurf/mcp_config.json (Global) | .windsurfrules (Project)
• Protocols: STDIO, SSE
• Pricing: Free Tier / Pro ($15/mo)
• Best For: Engineers who want continuous real-time agent collaboration alongside fast code completions.

### MCP Configuration Example Save to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres", "postgresql://localhost/mydb"]
    }
  }
}

4. Cline

An open-source VS Code extension for autonomous software development. Cline requests explicit human approval for shell commands and file edits while tracking real-time token costs per prompt pass.

• Type: Open Source VS Code Extension
• Config Path: cline_mcp_settings.json in VS Code Global Storage | .clinerules
• Protocols: STDIO, SSE
• Pricing: 100% Free & Open Source (Bring Your Own API Key)
• Best For: Developers who demand complete transparency, cost tracking, and human-in-the-loop security control.

### MCP Configuration Example Save in Cline Settings > MCP Servers:

{
  "mcpServers": {
    "playwright": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-playwright"]
    }
  }
}

5. Roo Code (Roo Vet)

An open-source community extension (derived from Cline) featuring multi-mode agent specialization (Code Mode, Architect Mode, Ask Mode, Test Mode, and custom modes).

• Type: Open Source VS Code Extension
• Config Path: ~/.vscode/extensions/roo-code/mcp_settings.json | .roomodes
• Protocols: STDIO, SSE
• Pricing: Free & Open Source (Bring Your Own API Key)
• Best For: Power users who want dedicated agent personas and mode-level prompt engineering.

### MCP Configuration Example

{
  "mcpServers": {
    "memory": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-memory"]
    }
  }
}

6. Aider

A terminal-based AI pair programming CLI created by Paul Gauthier. Aider automatically creates a Git commit for every accepted code modification, providing an immutable audit trail and trivial rollback capability.

• Type: Git-Centric Terminal CLI
• Config Path: .aider.conf.yml (Project) | ~/.aider.conf.yml (Global)
• Protocols: Git API, Custom LLM Provider APIs
• Pricing: Free & Open Source (Bring Your Own API Key)
• Best For: Developers who want git-anchored commits, automated test loops, and seamless command-line pair programming.

### Configuration Example Save to .aider.conf.yml:

model: claude-3-7-sonnet-20250219
auto-commits: true
lint-cmd: npm run lint
test-cmd: npm test

7. Continue

An open-source AI assistant extension supporting both VS Code and JetBrains IDEs (IntelliJ IDEA, PyCharm, WebStorm, GoLand).

• Type: Open Source Extension (VS Code & JetBrains)
• Config Path: ~/.continue/config.json
• Protocols: STDIO, Custom MCP Integrations
• Pricing: Free & Open Source (Supports local LLMs via Ollama & Cloud APIs)
• Best For: JetBrains IDE users and teams requiring strict on-premise local model privacy.

### MCP Configuration Example Save to ~/.continue/config.json:

{
  "mcpServers": [
    {
      "name": "sqlite",
      "command": "uvx",
      "args": ["mcp-server-sqlite", "--db-path", "./app.db"]
    }
  ]
}

8. Claude Desktop

Anthropic's official desktop application featuring full Model Context Protocol (MCP) server support, artifact visualization, and file attachments.

• Type: Desktop Application
• Config Path: macOS: ~/Library/Application Support/Claude/claude_desktop_config.json<br>Windows: %APPDATA%\Claude\claude_desktop_config.json
• Protocols: STDIO, SSE
• Pricing: Free / Pro ($20/mo) / Team
• Best For: Knowledge workers, researchers, and developers who want official Anthropic MCP server extensions.

### Configuration Example

{
  "mcpServers": {
    "fetch": {
      "command": "uvx",
      "args": ["mcp-server-fetch"]
    }
  }
}

9. VS Code + GitHub Copilot (Official MCP)

Microsoft's native VS Code agent integration supporting MCP servers, workspace indexing, and multi-file code editing within the standard Copilot Chat panel.

• Type: Official IDE Integration
• Config Path: .vscode/mcp.json or User Settings
• Protocols: STDIO, SSE, HTTP
• Pricing: GitHub Copilot Individual ($10/mo) / Business / Enterprise
• Best For: Enterprise developers already embedded in the Microsoft & GitHub Copilot ecosystem.

10. Zed Assistant

An ultra-fast, GPU-accelerated code editor written in Rust with built-in AI assistant panels, multi-model support, and inline transformation prompts.

• Type: High-Performance Rust IDE
• Config Path: ~/.config/zed/settings.json
• Protocols: Language Server Protocol, Provider APIs
• Pricing: Free & Open Source / Zed Credits
• Best For: Speed enthusiasts who want instantaneous editor response times paired with LLM completions.

Decision Matrix: How to Choose Your Harness

1. Terminal vs. IDE Interface:

• Prefer terminal freedom? Pick Claude Code or Aider.
• Prefer a ready-to-use editor? Pick Cursor or Windsurf.
• Prefer VS Code extensions? Pick Cline or Roo Code.
• Using JetBrains? Pick Continue.

1. Pricing & Billing Preference:

• Fixed Monthly Subscription: Cursor ($20/mo), Windsurf ($15/mo), Claude Pro ($20/mo), Copilot ($10/mo).
• Pay-per-token (BYOK): Cline, Roo Code, Aider, Continue (gives complete cost transparency per request).
• Local / Privacy-first: Continue or Aider paired with Ollama or LM Studio.

1. System Rules & Context Files:

• Claude Code reads CLAUDE.md.
• Cursor reads .cursor/rules/*.mdc or .cursorrules.
• Windsurf reads .windsurfrules.
• Cline reads .clinerules.
• All client harnesses support AGENTS.md standard project rules.

Next Steps

• Browse our MCP Server Directory to find tools compatible with your harness.
• Explore Skill Packages for executable agent workflow specifications.
• Copy production-ready system rules from our Templates Collection.