diff --git a/README.md b/README.md
index b411b9f..3808fe8 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,11 @@ A Python library for hierarchical configuration management with inheritance, cro
 
 ## Installation
 
+```bash
+pip install configurize
+```
+
+for development
 ```bash
 pip install .
 ```
diff --git a/configurize/__init__.py b/configurize/__init__.py
index dc92b7e..a8ab5ef 100644
--- a/configurize/__init__.py
+++ b/configurize/__init__.py
@@ -1,5 +1,5 @@
 from .allowed_types import ALLOWED_TYPES, recur_to_allowed_types
-from .config import Config, ConfigDiff, config_diff
+from .config import Config, ConfigDiff, TaskSpec, config_diff
 from .data_class import DataClass
 from .reference import Ref
 from .utils import writable_property
diff --git a/configurize/config.py b/configurize/config.py
index a9ce817..0c78bb3 100644
--- a/configurize/config.py
+++ b/configurize/config.py
@@ -5,7 +5,7 @@
 import weakref
 from contextlib import contextmanager
 from functools import partial
-from typing import Any, Callable
+from typing import Any, Callable, TypedDict
 
 from loguru import logger
 
@@ -15,6 +15,21 @@
 from .utils import get_func_brief, writable_property
 
 
+class TaskSpec(TypedDict, total=False):
+    """Indicate resource & entrypoint for specific task.
+    Below attributes DO NOT need default value if not set.
+    """
+
+    replica: int
+    """Number of replica(nodes) this task should run on."""
+    command: str
+    """Entrypoint for this task. e.g. 'redis-server --port 12345'"""
+    envs: dict[str, Any]
+    """Environment variables for this task."""
+    image: str
+    """Docker image for this task. Optional."""
+
+
 class Config(DataClass):
     """Base Config Type, like dataclass, extra support:
     - config.sub_config = SubConfig()
@@ -71,9 +86,8 @@ class Config(DataClass):
     - key2 must same as in expected_cfg[key2] if it exists in expected_cfg.
     """
 
-    task_specs: dict[str, dict]
-    """If set, this module requires an individual sub-task. Adding this should be equal to add task to 
-    ResourceConfig.task_specs
+    task_specs: dict[str, TaskSpec]
+    """If set, this module requires somes individual entrypoints.
     """
 
     @writable_property
@@ -105,6 +119,16 @@ def root(self) -> "Config":
     def assert_critical_attrs_expected(
         self, expected_cfg: "dict | Config", cum_errs: list = None
     ):
+        """Recursively compare self with another 'expected_cfg', raise error
+        if any of 'critical_keys' mismatches.
+
+        Args:
+            expected_cfg (dict | Config): The reference config, NOTE: only critical_keys of
+            THIS(self) config will be checked.
+
+        Raises:
+            Exception: raise all mismatch keys.
+        """
         errs = []  # hold error and raise together
         # recursive check sub nodes
         for k, v in self.items():
@@ -150,13 +174,6 @@ def assert_critical_attrs_expected(
                 text = "\n".join(text)
                 raise Exception(f"{text}\nAttributes Check Fail!")
 
-    def _ensure_exp_args_parsed(self):
-        """Ensure CLI overrides are applied by running update_from_args once."""
-        root = self.root()
-        updater = getattr(root, "update_from_args", None)
-        if callable(updater):
-            updater()
-
     def _deref(self, name, value, deref=True):
         if isinstance(value, Ref):
             try:
@@ -235,7 +252,7 @@ def __setattr__(self, name: str, value: Any) -> None:
             self._set_attribute_traces[name].append((value, caller_info, defined))
         return super().__setattr__(name, value)
 
-    def _all_set_history(self):
+    def _all_set_history(self) -> dict[str, list[tuple[Any, str, bool]]]:
         history = {}
         if self._set_attribute_traces:
             for k, trace in self._set_attribute_traces.items():
@@ -246,6 +263,10 @@ def _all_set_history(self):
         return history
 
     def __init__(self, **kwargs):
+        """
+        1. set kwargs on self.
+        2. build all my sub-configs.
+        """
         self._merge_args(kwargs)
 
         for k, v in self.items(deref=False):