MCP Context

from fastmcp import FastMCP
from fastmcp.dependencies import CurrentContext
from fastmcp.server.context import Context

mcp = FastMCP(name="Context Demo")

@mcp.tool
async def process_file(file_uri: str, ctx: Context = CurrentContext()) -> str:
    """Processes a file, using context for logging and resource access."""
    await ctx.info(f"Processing {file_uri}")
    return "Processed file"

from fastmcp import FastMCP, Context

mcp = FastMCP(name="Context Demo")

@mcp.tool
async def process_file(file_uri: str, ctx: Context) -> str:
    """Processes a file, using context for logging and resource access."""
    # Context is injected automatically based on the type hint
    return "Processed file"

from fastmcp import FastMCP
from fastmcp.server.dependencies import get_context

mcp = FastMCP(name="Dependency Demo")

# Utility function that needs context but doesn't receive it as a parameter
async def process_data(data: list[float]) -> dict:
    # Get the active context - only works when called within a request
    ctx = get_context()
    await ctx.info(f"Processing {len(data)} data points")

@mcp.tool
async def analyze_dataset(dataset_name: str) -> dict:
    # Call utility function that uses context internally
    data = load_data(dataset_name)
    await process_data(data)

from fastmcp.server.middleware import Middleware, MiddlewareContext

class UserAuthMiddleware(Middleware):
    async def on_call_tool(self, context: MiddlewareContext, call_next):

        # Middleware stores user info in context state
        context.fastmcp_context.set_state("user_id", "user_123")
        context.fastmcp_context.set_state("permissions", ["read", "write"])

        return await call_next(context)

@mcp.tool
async def secure_operation(data: str, ctx: Context) -> str:
    """Tool can access state set by middleware."""

    user_id = ctx.get_state("user_id")  # "user_123"
    permissions = ctx.get_state("permissions")  # ["read", "write"]
    
    if "write" not in permissions:
        return "Access denied"
    
    return f"Processing {data} for user {user_id}"

from fastmcp import FastMCP
from fastmcp.server.dependencies import get_http_request
from starlette.requests import Request

mcp = FastMCP(name="HTTP Request Demo")

@mcp.tool
async def user_agent_info() -> dict:
    """Return information about the user agent."""
    # Get the HTTP request
    request: Request = get_http_request()
    
    # Access request data
    user_agent = request.headers.get("user-agent", "Unknown")
    client_ip = request.client.host if request.client else "Unknown"
    
    return {
        "user_agent": user_agent,
        "client_ip": client_ip,
        "path": request.url.path,
    }

from fastmcp import FastMCP
from fastmcp.server.dependencies import get_http_headers

mcp = FastMCP(name="Headers Demo")

@mcp.tool
async def safe_header_info() -> dict:
    """Safely get header information without raising errors."""
    # Get headers (returns empty dict if no request context)
    headers = get_http_headers()
    
    # Get authorization header
    auth_header = headers.get("authorization", "")
    is_bearer = auth_header.startswith("Bearer ")
    
    return {
        "user_agent": headers.get("user-agent", "Unknown"),
        "content_type": headers.get("content-type", "Unknown"),
        "has_auth": bool(auth_header),
        "auth_type": "Bearer" if is_bearer else "Other" if auth_header else "None",
        "headers_count": len(headers)
    }

from fastmcp import FastMCP
from fastmcp.server.dependencies import get_access_token, AccessToken

mcp = FastMCP(name="Auth Token Demo")

@mcp.tool
async def get_user_info() -> dict:
    """Get information about the authenticated user."""
    # Get the access token (None if not authenticated)
    token: AccessToken | None = get_access_token()
    
    if token is None:
        return {"authenticated": False}
    
    return {
        "authenticated": True,
        "client_id": token.client_id,
        "scopes": token.scopes,
        "expires_at": token.expires_at,
        "token_claims": token.claims,  # JWT claims or custom token data
    }

from fastmcp import FastMCP
from fastmcp.server.dependencies import get_access_token

mcp = FastMCP(name="Multi-tenant Demo")

@mcp.tool
async def get_tenant_data(resource_id: str) -> dict:
    """Get tenant-specific data using token claims."""
    token: AccessToken | None = get_access_token()
    
    # Extract tenant ID from token claims
    tenant_id = token.claims.get("tenant_id") if token else None
    
    # Extract user ID from standard JWT subject claim
    user_id = token.claims.get("sub") if token else None
    
    # Use tenant and user info to authorize and filter data
    if not tenant_id:
        raise ValueError("No tenant information in token")
    
    return {
        "resource_id": resource_id,
        "tenant_id": tenant_id,
        "user_id": user_id,
        "data": f"Tenant-specific data for {tenant_id}",
    }