MCP & Tool Integration: Connecting Agents to the World

An Agent without tools is just a chatbot. MCP gives Agents a standardized "plug" — connect once, work everywhere.

🤔 Why Agents Need Tools

LLMs alone can only generate text. To make Agents actually do work — read files, query databases, call APIs, operate browsers — they need tools.

The problem: N models × M tools = N×M custom integrations. Every model connecting to every tool needs bespoke code. This is integration hell.

MCP (Model Context Protocol) solves this.

📖 What MCP Is

MCP is an open protocol originally released by Anthropic in November 2024, transferred to the Linux Foundation in late 2025. It defines a unified standard for AI applications to connect to external tools and data sources.

Analogy: USB-C. Every phone maker used to have their own charging port. Now it's all USB-C. MCP is the USB-C of the AI world.

Three core primitives:

Primitive	What it does	Example
Resources	Provides readable data	File contents, DB records, API responses
Tools	Provides callable functions	list_issues, send_email, run_query
Prompts	Provides reusable prompt templates	"Code review template", "Daily report template"

Three roles:

Host (e.g., Claude Desktop, IDE plugin)
  → Client (connection handler inside the host)
    → Server (service providing capabilities)

Learn more: MCP Protocol Deep Dive →

🔧 How to Use MCP

Scenario 1: Connect GitHub to Claude

# 1. Install GitHub MCP Server
npm install -g @modelcontextprotocol/server-github

# 2. Configure Claude Desktop
# Add to claude_desktop_config.json:
{
  "mcpServers": {
    "github": {
      "command": "node",
      "args": ["@modelcontextprotocol/server-github"],
      "env": { "GITHUB_TOKEN": "your-token" }
    }
  }
}

# 3. Restart Claude Desktop
# Now Claude can directly check Issues, create PRs

Scenario 2: Connect a Database to Hermes Agent

# 1. Install PostgreSQL MCP Server
hermes mcp add postgres --command "node" --args ["@modelcontextprotocol/server-postgres"]

# 2. Configure connection
hermes mcp config postgres --env "DATABASE_URL=postgresql://..."

# 3. Use it
> Query last month's order data
# Hermes queries the database directly via MCP Server

Scenario 3: Build Your Own MCP Server

# Minimal MCP Server example (Python)
from mcp.server import Server

server = Server("my-tool")

@server.tool()
def get_weather(city: str) -> str:
    """Get weather for a city"""
    # Call weather API
    return f"{city}: sunny, 25°C today"

server.run()

Key point: Tools must declare parameters with JSON Schema so the LLM knows how to call them.

📊 MCP Server Ecosystem

Category	Server	What it does
Dev	GitHub	Issues, PRs, code search
Dev	GitLab	Project management, code review
Database	PostgreSQL	Query, analyze
Database	SQLite	Local data operations
Search	Brave Search	Web search
Browser	Puppeteer	Web operations, screenshots
Files	FileSystem	Read/write local files
Communication	Slack	Send messages, read channels
Communication	Email	Send emails
AI	Hugging Face	Model inference

More servers: MCP Official Repository →

🆚 MCP vs Other Integration Approaches

Approach	Pros	Cons	Best for
MCP	Standardized, reusable, rich ecosystem	Need to learn the protocol	Multi-tool, multi-model scenarios
Direct API	Simple and direct	Custom integration per tool	Single, one-off integrations
Function Calling	Native model support	Different format per model	Single-model scenarios
Framework built-in	Out of the box	Locked to framework	Quick prototyping

Selection advice:

• 1-2 tools + 1 model → Direct API or Function Calling
• Many tools + many models → MCP
• Quick experiment → Framework built-in tools
• Production deployment → MCP + permission controls

⚠️ MCP Security Considerations

MCP Servers can execute real operations (delete files, send emails, modify databases). Security matters:

Risk	Defense
Agent calls dangerous operations	Set approval mechanisms (high-risk ops need human confirmation)
MCP Server has excessive permissions	Least privilege principle (only grant needed permissions)
Data leakage	Server-side filtering of sensitive information
Supply chain risk	Only use trusted MCP Servers, audit source code

Best practices:

1. High-risk operations (delete, push, pay) must require human approval
2. Minimize MCP Server permissions
3. Log all tool calls
4. Regularly audit MCP Server sources

🔗 Further Reading

• MCP Protocol Deep Dive → — Protocol specification in detail
• How Agents Work → — Where tools fit in the Agent loop
• Agent Framework Guide → — Framework MCP support comparison
• Hermes Agent → — An open-source Agent with MCP support
• Tool Use Pattern → — How Agents choose and use tools