Migrate to native @app.mcp_tool() decorators (azure-functions 1.25.0b2)

README.md

@@ -274,84 +274,50 @@ azd deploy
 
 The function code for the `get_snippet` and `save_snippet` endpoints are defined in the Python files in the `src` directory. The MCP function annotations expose these functions as MCP Server tools.
 
-Here's the actual code from the function_app.py file:
+Here's the actual code from the function_app.py file using the new `@app.mcp_tool()` decorators (requires `azure-functions>=1.25.0b2`):
 
 ```python
 
-@app.generic_trigger(arg_name="context", type="mcpToolTrigger", toolName="hello", 
-                     description="Hello world.", 
-                     toolProperties="[]")
-def hello_mcp(context) -> None:
-    """
-    A simple function that returns a greeting message.
-
-    Args:
-        context: The trigger context (not used in this function).
-
-    Returns:
-        str: A greeting message.
-    """
+@app.mcp_tool()
+def hello_mcp() -> str:
+    """Hello world."""
     return "Hello I am MCPTool!"
 
 
-@app.generic_trigger(
-    arg_name="context",
-    type="mcpToolTrigger",
-    toolName="getsnippet",
-    description="Retrieve a snippet by name.",
-    toolProperties=tool_properties_get_snippets_json
-)
-@app.generic_input_binding(
-    arg_name="file",
-    type="blob",
-    connection="AzureWebJobsStorage",
-    path=_BLOB_PATH
-)
-def get_snippet(file: func.InputStream, context) -> str:
-    """
-    Retrieves a snippet by name from Azure Blob Storage.
-
-    Args:
-        file (func.InputStream): The input binding to read the snippet from Azure Blob Storage.
-        context: The trigger context containing the input arguments.
-
-    Returns:
-        str: The content of the snippet or an error message.
-    """
+@app.mcp_tool()
+@app.mcp_tool_property(arg_name="snippetname", description="The name of the snippet.")
+@app.blob_input(arg_name="file", connection="AzureWebJobsStorage", path=_BLOB_PATH)
+def get_snippet(file: func.InputStream, snippetname: str) -> str:
+    """Retrieve a snippet by name from Azure Blob Storage."""
     snippet_content = file.read().decode("utf-8")
     logging.info(f"Retrieved snippet: {snippet_content}")
     return snippet_content
 
 
-@app.generic_trigger(
-    arg_name="context",
-    type="mcpToolTrigger",
-    toolName="savesnippet",
-    description="Save a snippet with a name.",
-    toolProperties=tool_properties_save_snippets_json
-)                   
-@app.generic_output_binding(
-    arg_name="file",
-    type="blob",
-    connection="AzureWebJobsStorage",
-    path=_BLOB_PATH
-)
-def save_snippet(file: func.Out[str], context) -> str:
-    content = json.loads(context)
-    snippet_name_from_args = content["arguments"][_SNIPPET_NAME_PROPERTY_NAME]
-    snippet_content_from_args = content["arguments"][_SNIPPET_PROPERTY_NAME]
-
-    if not snippet_name_from_args:
+@app.mcp_tool()
+@app.mcp_tool_property(arg_name="snippetname", description="The name of the snippet.")
+@app.mcp_tool_property(arg_name="snippet", description="The content of the snippet.")
+@app.blob_output(arg_name="file", connection="AzureWebJobsStorage", path=_BLOB_PATH)
+def save_snippet(file: func.Out[str], snippetname: str, snippet: str) -> str:
+    """Save a snippet to Azure Blob Storage."""
+    if not snippetname:
         return "No snippet name provided"
-
-    if not snippet_content_from_args:
+    if not snippet:
         return "No snippet content provided"
- 
-    file.set(snippet_content_from_args)
-    logging.info(f"Saved snippet: {snippet_content_from_args}")
-    return f"Snippet '{snippet_content_from_args}' saved successfully"
+
+    file.set(snippet)
+    logging.info(f"Saved snippet: {snippet}")
+    return f"Snippet '{snippetname}' saved successfully with content: {snippet}"
 ```
 
+Key features of the new MCP decorators:
+- `@app.mcp_tool()` replaces `@app.generic_trigger(type="mcpToolTrigger", ...)`
+- Tool properties are inferred from function signatures and type hints
+- `@app.mcp_tool_property()` explicitly defines tool property descriptions
+- `@app.blob_input()` and `@app.blob_output()` replace generic bindings
+- No manual JSON parsing required - arguments arrive as function parameters
+- Tool descriptions come from function docstrings
+
 Note that the `host.json` file also includes a reference to the experimental bundle, which is required for apps using this feature:
 
 ```json

infra/app/api.bicep

@@ -35,6 +35,9 @@ var baseAppSettings = {
   // Application Insights settings are always included
   APPLICATIONINSIGHTS_AUTHENTICATION_STRING: applicationInsightsIdentity
   APPLICATIONINSIGHTS_CONNECTION_STRING: applicationInsights.properties.ConnectionString
+
+  // Required for MCP decorators (azure-functions 1.25.0b2+)
+  PYTHON_ISOLATE_WORKER_DEPENDENCIES: '1'
 }
 
 // Dynamically build storage endpoint settings based on feature flags

src/function_app.py

@@ -1,4 +1,3 @@
-import json
 import logging
 
 import azure.functions as func
@@ -11,96 +10,33 @@
 _BLOB_PATH = "snippets/{mcptoolargs." + _SNIPPET_NAME_PROPERTY_NAME + "}.json"
 
 
-class ToolProperty:
-    def __init__(self, property_name: str, property_type: str, description: str):
-        self.propertyName = property_name
-        self.propertyType = property_type
-        self.description = description
-
-    def to_dict(self):
-        return {
-            "propertyName": self.propertyName,
-            "propertyType": self.propertyType,
-            "description": self.description,
-        }
-
-
-# Define the tool properties using the ToolProperty class
-tool_properties_save_snippets_object = [
-    ToolProperty(_SNIPPET_NAME_PROPERTY_NAME, "string", "The name of the snippet."),
-    ToolProperty(_SNIPPET_PROPERTY_NAME, "string", "The content of the snippet."),
-]
-
-tool_properties_get_snippets_object = [ToolProperty(_SNIPPET_NAME_PROPERTY_NAME, "string", "The name of the snippet.")]
-
-# Convert the tool properties to JSON
-tool_properties_save_snippets_json = json.dumps([prop.to_dict() for prop in tool_properties_save_snippets_object])
-tool_properties_get_snippets_json = json.dumps([prop.to_dict() for prop in tool_properties_get_snippets_object])
-
-
-@app.generic_trigger(
-    arg_name="context",
-    type="mcpToolTrigger",
-    toolName="hello_mcp",
-    description="Hello world.",
-    toolProperties="[]",
-)
-def hello_mcp(context) -> None:
-    """
-    A simple function that returns a greeting message.
-
-    Args:
-        context: The trigger context (not used in this function).
-
-    Returns:
-        str: A greeting message.
-    """
+@app.mcp_tool()
+def hello_mcp() -> str:
+    """Hello world."""
     return "Hello I am MCPTool!"
 
 
-@app.generic_trigger(
-    arg_name="context",
-    type="mcpToolTrigger",
-    toolName="get_snippet",
-    description="Retrieve a snippet by name.",
-    toolProperties=tool_properties_get_snippets_json,
-)
-@app.generic_input_binding(arg_name="file", type="blob", connection="AzureWebJobsStorage", path=_BLOB_PATH)
-def get_snippet(file: func.InputStream, context) -> str:
-    """
-    Retrieves a snippet by name from Azure Blob Storage.
-
-    Args:
-        file (func.InputStream): The input binding to read the snippet from Azure Blob Storage.
-        context: The trigger context containing the input arguments.
-
-    Returns:
-        str: The content of the snippet or an error message.
-    """
+@app.mcp_tool()
+@app.mcp_tool_property(arg_name="snippetname", description="The name of the snippet.")
+@app.blob_input(arg_name="file", connection="AzureWebJobsStorage", path=_BLOB_PATH)
+def get_snippet(file: func.InputStream, snippetname: str) -> str:
+    """Retrieve a snippet by name from Azure Blob Storage."""
     snippet_content = file.read().decode("utf-8")
     logging.info(f"Retrieved snippet: {snippet_content}")
     return snippet_content
 
 
-@app.generic_trigger(
-    arg_name="context",
-    type="mcpToolTrigger",
-    toolName="save_snippet",
-    description="Save a snippet with a name.",
-    toolProperties=tool_properties_save_snippets_json,
-)
-@app.generic_output_binding(arg_name="file", type="blob", connection="AzureWebJobsStorage", path=_BLOB_PATH)
-def save_snippet(file: func.Out[str], context) -> str:
-    content = json.loads(context)
-    snippet_name_from_args = content["arguments"][_SNIPPET_NAME_PROPERTY_NAME]
-    snippet_content_from_args = content["arguments"][_SNIPPET_PROPERTY_NAME]
-
-    if not snippet_name_from_args:
+@app.mcp_tool()
+@app.mcp_tool_property(arg_name="snippetname", description="The name of the snippet.")
+@app.mcp_tool_property(arg_name="snippet", description="The content of the snippet.")
+@app.blob_output(arg_name="file", connection="AzureWebJobsStorage", path=_BLOB_PATH)
+def save_snippet(file: func.Out[str], snippetname: str, snippet: str) -> str:
+    """Save a snippet to Azure Blob Storage."""
+    if not snippetname:
         return "No snippet name provided"
-
-    if not snippet_content_from_args:
+    if not snippet:
         return "No snippet content provided"
 
-    file.set(snippet_content_from_args)
-    logging.info(f"Saved snippet: {snippet_content_from_args}")
-    return f"Snippet '{snippet_content_from_args}' saved successfully"
+    file.set(snippet)
+    logging.info(f"Saved snippet: {snippet}")
+    return f"Snippet '{snippetname}' saved successfully with content: {snippet}"

src/local.settings.json

@@ -2,6 +2,7 @@
     "IsEncrypted": false,
     "Values": {
       "FUNCTIONS_WORKER_RUNTIME": "python",
-      "AzureWebJobsStorage": "UseDevelopmentStorage=true"
+      "AzureWebJobsStorage": "UseDevelopmentStorage=true",
+      "PYTHON_ISOLATE_WORKER_DEPENDENCIES": "1"
     }
   }

src/requirements.txt

@@ -2,4 +2,4 @@
 # The Python Worker is managed by the Azure Functions platform
 # Manually managing azure-functions-worker may cause unexpected issues
 
-azure-functions
+azure-functions==1.25.0b2