diff --git a/pyproject.toml b/pyproject.toml
index 0709c92..7297436 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,13 +10,25 @@ skips = ["*/*test.py", "*/test_*.py", "*tests/*.py"]
 [tool.coverage.run]
 branch = true
 
+[tool.coverage.report]
+fail_under = 99
+show_missing = true
+
+[tool.pytest.ini_options]
+minversion = "6.0"
+log_cli_level = "INFO"
+
+[tool.pylint.'MESSAGES CONTROL']
+extension-pkg-whitelist = "pydantic"
+
 # Formatting tools configuration
 [tool.black]
 line-length = 99
-target-version = ["py38"]
+target-version = ["py310"]
 
-[tool.coverage.report]
-show_missing = true
+[tool.isort]
+line_length = 99
+profile = "black"
 
 # Linting tools configuration
 [tool.flake8]
@@ -28,54 +40,22 @@ select = ["E", "W", "F", "C", "N", "R", "D", "H"]
 # Ignore W503, E501 because using black creates errors with this
 # Ignore D107 Missing docstring in __init__
 ignore = ["W503", "E501", "D107"]
-# D100, D101, D102, D103: Ignore missing docstrings in tests
-per-file-ignores = ["tests/*:D100,D101,D102,D103,D104,D205,D212,D415"]
+# In tests we can ignore
+# D100, D101, D102, D103: missing docstrings
+# D205, D212: docstring formatting (1 blank line required, multiline docstring summary)
+per-file-ignores = ["tests/*:D100,D101,D102,D103,D104,D205,D212"]
 docstring-convention = "google"
-
-[tool.isort]
-line_length = 99
-profile = "black"
+# Check for properly formatted copyright header in each file
+copyright-check = "True"
+copyright-author = "Canonical Ltd."
+copyright-regexp = "Copyright\\s\\d{4}([-,]\\d{4})*\\s+%(author)s"
 
 [tool.mypy]
 ignore_missing_imports = true
-explicit_package_bases = true
 check_untyped_defs = true
-namespace_packages = true
+disallow_untyped_defs = true
 plugins = ["pydantic.mypy"]
 
-[tool.pylint]
-disable = "wrong-import-order"
-
-[tool.pylint.'MESSAGES CONTROL']
-extension-pkg-whitelist = "pydantic"
-
-[tool.pytest.ini_options]
-minversion = "6.0"
-log_cli_level = "INFO"
-
-# Linting tools configuration
-[tool.ruff]
-line-length = 99
-select = ["E", "W", "F", "C", "N", "D", "I001"]
-extend-ignore = [
-    "D203",
-    "D204",
-    "D213",
-    "D215",
-    "D400",
-    "D404",
-    "D406",
-    "D407",
-    "D408",
-    "D409",
-    "D413",
-]
-ignore = ["E501", "D107"]
-extend-exclude = ["__pycache__", "*.egg_info"]
-per-file-ignores = {"tests/*" = ["D100","D101","D102","D103","D104"]}
-
-[tool.ruff.mccabe]
-max-complexity = 10
-
-[tool.codespell]
-skip = "build,lib,venv,icon.svg,.tox,.git,.mypy_cache,.ruff_cache,.coverage"
+[[tool.mypy.overrides]]
+module = "tests.*"
+disallow_untyped_defs = false
\ No newline at end of file
diff --git a/src/charm.py b/src/charm.py
index c34c7c3..70bbef8 100755
--- a/src/charm.py
+++ b/src/charm.py
@@ -66,7 +66,7 @@ def _on_upgrade_charm(self, event: ops.UpgradeCharmEvent) -> None:
         """
         self.reconcile(event)
 
-    def reconcile(self, _: ops.EventBase):
+    def reconcile(self, _: ops.EventBase) -> None:
         """Reconciliation for the jenkins agent charm."""
         if not self.model.get_relation(AGENT_RELATION):
             self.model.unit.status = ops.WaitingStatus("Waiting for relation.")
diff --git a/src/service.py b/src/service.py
index 671748d..7db74d9 100644
--- a/src/service.py
+++ b/src/service.py
@@ -8,7 +8,7 @@
 
 from charms.operator_libs_linux.v2 import snap
 
-from charm_state import State
+from charm_state import Credentials, State
 
 logger = logging.getLogger(__name__)
 SNAP_NAME = "jenkins-agent"
@@ -46,7 +46,7 @@ def is_active(self) -> bool:
         service: dict = agent.services.get(SNAP_NAME)
         return bool(service.get("active"))
 
-    def install(self):
+    def install(self) -> None:
         """Install and set up the snap.
 
         Raises:
@@ -55,20 +55,22 @@ def install(self):
         try:
             cache = snap.SnapCache()
             agent = cache[SNAP_NAME]
-
             if not agent.present:
                 agent.ensure(snap.SnapState.Latest, classic=False, channel="latest/edge")
         except snap.SnapError as exc:
             raise SnapInstallError("Error installing the agent charm") from exc
 
-    def start(self):
+    def start(self) -> None:
         """Start the agent service."""
         cache = snap.SnapCache()
         agent = cache[SNAP_NAME]
+        credentials = self.state.agent_relation_credentials
+        if not credentials:
+            credentials = Credentials(address="", secret="")
         agent.set(
             {
-                "jenkins.token": self.state.agent_relation_credentials.secret,
-                "jenkins.url": self.state.agent_relation_credentials.address,
+                "jenkins.token": credentials.secret,
+                "jenkins.url": credentials.address,
                 "jenkins.agent": self.state.agent_meta.name,
             }
         )
diff --git a/tox.ini b/tox.ini
index ea2fca3..d138ba6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -54,6 +54,7 @@ deps =
     requests
     types-PyYAML
     types-requests
+    jenkinsapi>=0.3,<1
     -r{toxinidir}/requirements.txt
 commands =
     pydocstyle {[vars]src_path}