Azure Functions Development Skill
Overview
This skill helps you build Azure Functions using the Python v2 programming model with decorators.
Key Patterns
HTTP Trigger Function
python
import azure.functions as func
import json
app = func.FunctionApp(http_auth_level=func.AuthLevel.FUNCTION)
@app.function_name(name="my_function")
@app.route(route="api/endpoint", methods=["GET", "POST"])
def my_function(req: func.HttpRequest) -> func.HttpResponse:
"""HTTP trigger function with proper error handling."""
try:
# Parse request
data = req.get_json() if req.method == "POST" else dict(req.params)
# Your logic here
result = {"status": "success", "data": data}
return func.HttpResponse(
body=json.dumps(result),
status_code=200,
mimetype="application/json"
)
except Exception as e:
return func.HttpResponse(
body=json.dumps({"error": str(e)}),
status_code=500,
mimetype="application/json"
)
MCP Tool Trigger
python
@app.generic_trigger(
arg_name="context",
type="mcpToolTrigger",
toolName="my_tool",
description="What this tool does and when to use it",
toolProperties='[{"propertyName": "input", "propertyType": "string", "description": "The input parameter"}]'
)
def my_tool(context) -> str:
"""MCP tool function."""
content = json.loads(context)
input_value = content["arguments"].get("input", "")
return json.dumps({"result": input_value})
Configuration Files
host.json (Runtime Config)
json
{
"version": "2.0",
"extensionBundle": {
"id": "Microsoft.Azure.Functions.ExtensionBundle",
"version": "[4.*, 5.0.0)"
},
"extensions": {
"mcp": {
"enabled": true
}
}
}
local.settings.json (Local Development)
json
{
"IsEncrypted": false,
"Values": {
"FUNCTIONS_WORKER_RUNTIME": "python",
"AzureWebJobsStorage": "UseDevelopmentStorage=true",
"AzureWebJobsFeatureFlags": "EnableWorkerIndexing"
}
}
Local Development Commands
bash
# Start Azurite storage emulator (required) azurite --silent --location /tmp/azurite # Start the function app locally cd src/function_app_directory func start # Install Azure Functions Core Tools (macOS) brew tap azure/functions brew install azure-functions-core-tools@4
Deployment with Azure Developer CLI
bash
# Initialize project from template azd init --template <template-name> -e <environment-name> # Deploy to Azure azd up # Get function keys az functionapp keys list --resource-group <rg> --name <app-name>
Common Issues and Solutions
| Issue | Solution |
|---|---|
AzureWebJobsStorage error | Start Azurite: azurite --silent |
| Functions not discovered | Ensure host.json has correct extension bundle |
| MCP tools not showing | Check mcp.enabled: true in host.json extensions |
| 401 Unauthorized | Include x-functions-key header for FUNCTION auth level |
Best Practices
- •Always use type hints for better IDE support
- •Log important operations with
logging.info()andlogging.error() - •Return JSON responses with appropriate status codes
- •Use FUNCTION auth level for production (not ANONYMOUS)
- •Test locally with
func startbefore deploying