invoke_lambda_function_impl

Execute AWS Lambda functions with JSON payloads to access private resources, real-time data, or custom computations through the MCP2Lambda server.

Instructions

Tool that invokes an AWS Lambda function with a JSON payload. Before using this tool, list the functions available to you.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`function_name`	Yes
`parameters`	Yes

Implementation Reference

main.py:94-120 (handler)

The core handler function for the 'invoke_lambda_function_impl' tool. Validates the function name, invokes the AWS Lambda function using boto3, handles errors, and formats the response payload.

def invoke_lambda_function_impl(function_name: str, parameters: dict, ctx: Context) -> str:
    """Tool that invokes an AWS Lambda function with a JSON payload.
    Before using this tool, list the functions available to you."""
    
    if not validate_function_name(function_name):
        return f"Function {function_name} is not valid"

    ctx.info(f"Invoking {function_name} with parameters: {parameters}")

    response = lambda_client.invoke(
        FunctionName=function_name,
        InvocationType="RequestResponse",
        Payload=json.dumps(parameters),
    )

    ctx.info(f"Function {function_name} returned with status code: {response['StatusCode']}")

    if "FunctionError" in response:
        error_message = f"Function {function_name} returned with error: {response['FunctionError']}"
        ctx.error(error_message)
        return error_message

    payload = response["Payload"].read()
    
    # Format the response payload
    return format_lambda_response(function_name, payload)

main.py:126-126 (registration)
Registration of the invoke_lambda_function_impl tool using the mcp.tool() decorator in the generic tools strategy.
```
mcp.tool()(invoke_lambda_function_impl)
```
main.py:182-182 (registration)
Fallback registration of the invoke_lambda_function_impl tool using the mcp.tool() decorator when dynamic registration fails.
```
mcp.tool()(invoke_lambda_function_impl)
```

main.py:35-38 (helper)

Helper function used by the handler to validate Lambda function names based on prefix or explicit list.

def validate_function_name(function_name: str) -> bool:
    """Validate that the function name is valid and can be called."""
    return function_name.startswith(FUNCTION_PREFIX) or function_name in FUNCTION_LIST

main.py:56-65 (helper)

Helper function used by the handler to format the Lambda response, preferring JSON pretty-printing.

def format_lambda_response(function_name: str, payload: bytes) -> str:
    """Format the Lambda function response payload."""
    try:
        # Try to parse the payload as JSON
        payload_json = json.loads(payload)
        return f"Function {function_name} returned: {json.dumps(payload_json, indent=2)}"
    except (json.JSONDecodeError, UnicodeDecodeError):
        # Return raw payload if not JSON
        return f"Function {function_name} returned payload: {payload}"

MCP2Lambda