diff --git a/pyproject.toml b/pyproject.toml
index 493a696..9c1d92a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "sonilo"
-version = "0.21.1"
+version = "0.21.2"
 description = "Official Python client for the Sonilo API"
 readme = "README.md"
 license = "MIT"
diff --git a/src/sonilo/_client.py b/src/sonilo/_client.py
index 0742d94..0726da1 100644
--- a/src/sonilo/_client.py
+++ b/src/sonilo/_client.py
@@ -32,12 +32,17 @@
 #: distinguishable from direct SDK use in server-side analytics.
 DEFAULT_CLIENT_NAME = "sdk-python"
 
+#: Where a missing-key error sends the user. The MCP server and the CLI print
+#: the same link, so an agent can hand it straight to the person.
+API_KEYS_URL = "https://platform.sonilo.com/dashboard/api-keys"
+
 
 def _resolve_api_key(api_key: Optional[str]) -> str:
     key = api_key or os.environ.get("SONILO_API_KEY")
     if not key:
         raise SoniloError(
-            "Missing API key: pass api_key= or set the SONILO_API_KEY environment variable"
+            "Missing API key: pass api_key= or set the SONILO_API_KEY environment "
+            f"variable. Create a key at {API_KEYS_URL}"
         )
     return key
 
diff --git a/src/sonilo/_version.py b/src/sonilo/_version.py
index 76f2458..3964f1e 100644
--- a/src/sonilo/_version.py
+++ b/src/sonilo/_version.py
@@ -1 +1 @@
-__version__ = "0.21.1"
+__version__ = "0.21.2"
diff --git a/tests/test_sync_client.py b/tests/test_sync_client.py
index ce0e5ce..b4a9d1b 100644
--- a/tests/test_sync_client.py
+++ b/tests/test_sync_client.py
@@ -6,7 +6,7 @@
 import respx
 
 import sonilo.resources.tasks as tasks_module
-from sonilo import Sonilo
+from sonilo import AsyncSonilo, Sonilo
 from sonilo._version import __version__
 from sonilo.errors import AuthenticationError, GenerationError, SoniloError
 from sonilo.resources.tasks import parse_music_result
@@ -74,6 +74,15 @@ def test_missing_api_key_raises(monkeypatch):
         Sonilo()
 
 
+def test_missing_api_key_error_links_to_the_keys_page(monkeypatch):
+    # The MCP server and the CLI print this link; an agent passes it on.
+    monkeypatch.delenv("SONILO_API_KEY", raising=False)
+    with pytest.raises(SoniloError, match="https://platform.sonilo.com/dashboard/api-keys"):
+        Sonilo()
+    with pytest.raises(SoniloError, match="https://platform.sonilo.com/dashboard/api-keys"):
+        AsyncSonilo()
+
+
 def test_env_api_key_used(monkeypatch):
     monkeypatch.setenv("SONILO_API_KEY", "sk_env")
     client = Sonilo()