diff --git a/docs/user_guide/defining-schema.md b/docs/user_guide/defining-schema.md
index 29a4d98..14203a7 100644
--- a/docs/user_guide/defining-schema.md
+++ b/docs/user_guide/defining-schema.md
@@ -39,3 +39,73 @@ required:
   - thing
   - user
 ```
+
+## Checking if a schema is valid
+
+When authoring a schema, how do you check if you schema is following the expected form? Jupyter Events offers a simple command line tool to validate your schema against its Jupyter Events metaschema.
+
+First, install the CLI:
+
+```
+pip install jupyter_events[cli]
+```
+
+Then, run the CLI against your schema:
+
+```
+jupyter events validate path/to/my_schema.json
+```
+
+The output will look like this, if it passes:
+
+```
+──────────────────────────────────── Validating the following schema ────────────────────────────────────
+
+    {
+      "$id": "http://event.jupyter.org/test",
+      "version": 1,
+      "title": "Simple Test Schema",
+      "description": "A simple schema for testing\n",
+      "type": "object",
+      "properties": {
+        "prop": {
+          "title": "Test Property",
+          "description": "Test property.",
+          "type": "string"
+        }
+      }
+    }
+
+──────────────────────────────────────────────── Results ────────────────────────────────────────────────
+
+✔ Nice work! This schema is valid.
+```
+
+or this if fails:
+
+```
+──────────────────────────────────── Validating the following schema ────────────────────────────────────
+
+    {
+      "$id": "http://event.jupyter.org/test",
+      "version": 1,
+      "title": "Simple Test Schema",
+      "description": "A simple schema for testing\n",
+      "type": "object",
+      "properties": {
+        "__badName": {
+          "title": "Test Property",
+          "description": "Test property.",
+          "type": "string"
+        }
+      }
+    }
+
+──────────────────────────────────────────────── Results ────────────────────────────────────────────────
+❌ The schema failed to validate.
+
+We found the following error with your schema:
+
+    '__badName' is an invalid property name because it starts with `__`. Properties starting with
+    'dunder' are reserved as special meta-fields for Jupyter Events to use.
+```
diff --git a/jupyter_events/cli.py b/jupyter_events/cli.py
new file mode 100644
index 0000000..a0d5091
--- /dev/null
+++ b/jupyter_events/cli.py
@@ -0,0 +1,62 @@
+import json
+import pathlib
+
+import click
+from jsonschema import ValidationError
+from rich.console import Console
+from rich.json import JSON
+from rich.markup import escape
+from rich.padding import Padding
+from rich.style import Style
+
+from jupyter_events.schema import EventSchema, EventSchemaLoadingError
+
+console = Console()
+
+
+@click.group()
+def main():
+    """A simple CLI tool to quickly validate JSON schemas against
+    Jupyter Event's custom validator.
+
+    You can see Jupyter Event's meta-schema here:
+
+        https://raw.githubusercontent.com/jupyter/jupyter_events/main/jupyter_events/schemas/event-metaschema.yml
+    """
+    pass
+
+
+@click.command()
+@click.argument("schema")
+def validate(schema):
+    """Validate a SCHEMA against Jupyter Event's meta schema.
+
+    SCHEMA can be a JSON/YAML string or filepath to a schema.
+    """
+    console.rule("Validating the following schema", style=Style(color="blue"))
+    # Soft load the schema without validating.
+    try:
+        _schema = EventSchema._load_schema(schema)
+    except EventSchemaLoadingError:
+        schema_path = pathlib.Path(schema)
+        _schema = EventSchema._load_schema(schema_path)
+    # Print what was found.
+    schema_json = JSON(json.dumps(_schema))
+    console.print(Padding(schema_json, (1, 0, 1, 4)))
+    # Now validate this schema against the meta-schema.
+    try:
+        EventSchema(_schema)
+        console.rule("Results", style=Style(color="green"))
+        out = Padding(
+            "[green]\u2714[white] Nice work! This schema is valid.", (1, 0, 1, 0)
+        )
+        console.print(out)
+    except ValidationError as err:
+        console.rule("Results", style=Style(color="red"))
+        console.print("[red]\u274c [white]The schema failed to validate.\n")
+        console.print("We found the following error with your schema:")
+        out = escape(str(err))
+        console.print(Padding(out, (1, 0, 1, 4)))
+
+
+main.add_command(validate)
diff --git a/jupyter_events/logger.py b/jupyter_events/logger.py
index ff0f55d..6e72414 100644
--- a/jupyter_events/logger.py
+++ b/jupyter_events/logger.py
@@ -245,10 +245,11 @@ def add_listener(
 
         Parameters
         ----------
+        modified: bool
+            If True (default), listens to the data after it has been mutated/modified
+            by the list of modifiers.
         schema_id: str
             $id of the schema
-        version: str
-            The schema version
         listener: Callable
             A callable function/method that executes when the named event occurs.
         """
diff --git a/jupyter_events/schema.py b/jupyter_events/schema.py
index a0a5f57..c1859c3 100644
--- a/jupyter_events/schema.py
+++ b/jupyter_events/schema.py
@@ -49,9 +49,7 @@ def __init__(
         self._schema = _schema
 
     def __repr__(self):
-        out = f"Validator class: {self._validator.__class__.__name__}\n"
-        out += f"Schema: {json.dumps(self._schema, indent=2)}"
-        return out
+        return json.dumps(self._schema, indent=2)
 
     @staticmethod
     def _load_schema(schema: Union[dict, str, PurePath]) -> dict:
diff --git a/jupyter_events/validators.py b/jupyter_events/validators.py
index e64d671..df230ef 100644
--- a/jupyter_events/validators.py
+++ b/jupyter_events/validators.py
@@ -27,10 +27,11 @@ def validate_schema(schema: dict):
     except ValidationError as err:
         reserved_property_msg = " does not match '^(?!__.*)'"
         if reserved_property_msg in str(err):
-            bad_property = str(err)[: -(len(reserved_property_msg))]
+            idx = str(err).find(reserved_property_msg)
+            bad_property = str(err)[:idx].strip()
             raise ValidationError(
                 f"{bad_property} is an invalid property name because it "
                 "starts with `__`. Properties starting with 'dunder' "
-                "are reserved for Jupyter Events."
+                "are reserved as special meta-fields for Jupyter Events to use."
             )
         raise err
diff --git a/pyproject.toml b/pyproject.toml
index d4a24b4..5e43b6f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -40,6 +40,9 @@ file = 'COPYING.md'
 [project.urls]
 Homepage = "http://jupyter.org"
 
+[project.scripts]
+jupyter-events = "jupyter_events.cli:main"
+
 [project.optional-dependencies]
 test = [
     "coverage",
@@ -47,6 +50,10 @@ test = [
     "pytest-cov",
     "pytest>=6.0",
 ]
+cli = [
+    "click",
+    "rich"
+]
 
 [tool.hatch.version]
 path = "jupyter_events/_version.py"