MCP: Model Context Protocol Guide

1from mcp.server.fastmcp import FastMCP
2import httpx
3from datetime import datetime
4
5mcp = FastMCP("weather-tools")
6
7@mcp.tool()
8def get_weather(city: str) -> str:
9    """Hent aktuel vejrudsigt for en by.
10
11    Args:
12        city: Byens navn, f.eks. 'Copenhagen'
13    """
14    # Using Open-Meteo (free, no API key needed)
15    geo = httpx.get(
16        "https://geocoding-api.open-meteo.com/v1/search",
17        params={"name": city, "count": 1}
18    ).json()
19
20    if not geo.get("results"):
21        return f"Kunne ikke finde byen: {city}"
22
23    lat = geo["results"][0]["latitude"]
24    lon = geo["results"][0]["longitude"]
25
26    weather = httpx.get(
27        "https://api.open-meteo.com/v1/forecast",
28        params={
29            "latitude": lat,
30            "longitude": lon,
31            "current": "temperature_2m,wind_speed_10m,weather_code"
32        }
33    ).json()
34
35    current = weather["current"]
36    return (
37        f"Vejr i {city}: "
38        f"{current['temperature_2m']}C, "
39        f"vind {current['wind_speed_10m']} km/t"
40    )
41
42@mcp.tool()
43def get_time(timezone: str = "Europe/Copenhagen") -> str:
44    """Hent aktuel tid i en given tidszone.
45
46    Args:
47        timezone: IANA timezone, f.eks. 'Europe/Copenhagen'
48    """
49    from zoneinfo import ZoneInfo
50    now = datetime.now(ZoneInfo(timezone))
51    return now.strftime("%Y-%m-%d %H:%M:%S %Z")
52
53if __name__ == "__main__":
54    mcp.run()

1{
2  "mcpServers": {
3    "weather": {
4      "command": "python",
5      "args": ["/path/to/weather_server.py"]
6    }
7  }
8}

1from mcp.server.fastmcp import FastMCP
2import sqlite3
3
4mcp = FastMCP("data-server")
5
6# Static resource
7@mcp.resource("config://app")
8def get_config() -> str:
9    """Returner applikationens konfiguration."""
10    return """
11    App: MyApp v2.1
12    Environment: production
13    Database: PostgreSQL 16
14    Cache: Redis 7
15    """
16
17# Dynamic resource with URI template
18@mcp.resource("db://customers/{customer_id}")
19def get_customer(customer_id: str) -> str:
20    """Hent kundedata fra database.
21
22    Args:
23        customer_id: Unikt kunde-ID
24    """
25    conn = sqlite3.connect("customers.db")
26    cursor = conn.execute(
27        "SELECT name, email, plan FROM customers WHERE id = ?",
28        (customer_id,)
29    )
30    row = cursor.fetchone()
31    conn.close()
32
33    if not row:
34        return f"Kunde {customer_id} ikke fundet"
35
36    return f"Navn: {row[0]}\nEmail: {row[1]}\nPlan: {row[2]}"
37
38# Tool that works with resources
39@mcp.tool()
40def search_customers(query: str) -> str:
41    """Soeg efter kunder i databasen.
42
43    Args:
44        query: Soegeord (navn eller email)
45    """
46    conn = sqlite3.connect("customers.db")
47    cursor = conn.execute(
48        "SELECT id, name, email FROM customers WHERE name LIKE ? OR email LIKE ? LIMIT 10",
49        (f"%{query}%", f"%{query}%")
50    )
51    results = cursor.fetchall()
52    conn.close()
53
54    if not results:
55        return "Ingen kunder fundet"
56
57    return "\n".join(
58        f"ID: {r[0]}, Navn: {r[1]}, Email: {r[2]}"
59        for r in results
60    )

1import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
2import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
3
4const server = new McpServer({
5  name: "weather-tools",
6  version: "1.0.0",
7});
8
9server.tool(
10  "get_weather",
11  "Hent aktuel vejrudsigt for en by",
12  { city: { type: "string", description: "Byens navn" } },
13  async ({ city }) => {
14    const geoRes = await fetch(
15      `https://geocoding-api.open-meteo.com/v1/search?name=${city}&count=1`
16    );
17    const geo = await geoRes.json();
18
19    if (!geo.results?.length) {
20      return { content: [{ type: "text", text: `By ikke fundet: ${city}` }] };
21    }
22
23    const { latitude, longitude } = geo.results[0];
24    const weatherRes = await fetch(
25      `https://api.open-meteo.com/v1/forecast?latitude=${latitude}&longitude=${longitude}&current=temperature_2m,wind_speed_10m`
26    );
27    const weather = await weatherRes.json();
28    const { temperature_2m, wind_speed_10m } = weather.current;
29
30    return {
31      content: [{
32        type: "text",
33        text: `Vejr i ${city}: ${temperature_2m}C, vind ${wind_speed_10m} km/t`
34      }]
35    };
36  }
37);
38
39const transport = new StdioServerTransport();
40await server.connect(transport);

1from mcp.server.fastmcp import FastMCP
2
3mcp = FastMCP("code-review-tools")
4
5@mcp.prompt()
6def review_code(code: str, language: str = "python") -> str:
7    """Generer en code review prompt.
8
9    Args:
10        code: Koden der skal reviewes
11        language: Programmeringssprog
12    """
13    return f"""Review denne {language} kode grundigt.
14
15Fokuser paa:
161. Bugs og logiske fejl
172. Sikkerhedsproblemer
183. Performance issues
194. Kode-kvalitet og laebarhed
205. Best practices for {language}
21
22Kode:
23```{language}
24{code}
25```
26
27Giv konkrete forbedringsforslag med kodeeksempler."""
28
29@mcp.prompt()
30def explain_error(error_message: str, context: str = "") -> str:
31    """Generer en prompt til at forklare en fejlbesked.
32
33    Args:
34        error_message: Den fulde fejlbesked
35        context: Ekstra kontekst om hvad der blev forsoeget
36    """
37    prompt = f"Forklar denne fejl og hvordan den fikses:\n\n{error_message}"
38    if context:
39        prompt += f"\n\nKontekst: {context}"
40    return prompt

1{
2  "mcpServers": {
3    "weather": {
4      "command": "python",
5      "args": ["weather_server.py"]
6    },
7    "database": {
8      "command": "python",
9      "args": ["db_server.py"],
10      "env": {
11        "DATABASE_URL": "postgresql://localhost/mydb"
12      }
13    },
14    "github": {
15      "command": "npx",
16      "args": ["-y", "@modelcontextprotocol/server-github"],
17      "env": {
18        "GITHUB_TOKEN": "ghp_..."
19      }
20    },
21    "filesystem": {
22      "command": "npx",
23      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/home/user/projects"]
24    }
25  }
26}