diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 929e5f504..4163ee3c1 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -40,6 +40,15 @@ uv run ruff check .
 uv run ruff format .
 ```
 
+OR use the Makefile:
+
+```bash
+make dev - Complete development setup and verification
+make lint - Run both linting and formatting
+make all - Run all quality checks
+make check - Fast parallel checking
+```
+
 7. Submit a pull request to the same branch you branched from
 
 ## Code Style
diff --git a/Makefile b/Makefile
new file mode 100644
index 000000000..b22625983
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,104 @@
+# Development Makefile for modelcontextprotocol-python-sdk
+
+# Variables
+PYTHON := uv run
+UV := uv
+
+# Default target
+.DEFAULT_GOAL := help
+
+# Phony targets
+.PHONY: help install sync test type-check lint-check lint-format lint clean all dev
+
+# Help command
+help:
+	@echo "Available commands:"
+	@echo "  make install      - Install dependencies with all extras and dev dependencies"
+	@echo "  make sync         - Sync dependencies (frozen, all extras, dev)"
+	@echo "  make test         - Run pytest tests"
+	@echo "  make type-check   - Run pyright type checker"
+	@echo "  make lint-check   - Run ruff linter checks"
+	@echo "  make lint-format  - Run ruff formatter"
+	@echo "  make lint         - Run both linter and formatter"
+	@echo "  make clean        - Clean cache files"
+	@echo "  make all          - Run all checks (test, type-check, lint)"
+	@echo "  make dev          - Setup dev environment and run all checks"
+
+# Install dependencies
+install:
+	$(UV) sync --all-extras --dev
+
+# Sync dependencies (frozen)
+sync:
+	$(UV) sync --frozen --all-extras --dev
+
+# Run tests
+test: sync
+	$(PYTHON) pytest
+
+# Run type checking
+type-check: sync
+	$(PYTHON) pyright
+
+# Run linter checks
+lint-check: sync
+	$(PYTHON) ruff check .
+
+# Run formatter
+lint-format: sync
+	$(PYTHON) ruff format .
+
+# Combined lint target
+lint: lint-check lint-format
+
+# Clean cache files
+clean:
+	find . -type d -name "__pycache__" -exec rm -rf {} + 2>/dev/null || true
+	find . -type d -name ".pytest_cache" -exec rm -rf {} + 2>/dev/null || true
+	find . -type d -name ".ruff_cache" -exec rm -rf {} + 2>/dev/null || true
+	find . -type d -name ".pyright" -exec rm -rf {} + 2>/dev/null || true
+	find . -type f -name "*.pyc" -delete 2>/dev/null || true
+
+# Run all checks
+all: test type-check lint
+
+# Development setup and run all checks
+dev: sync all
+	@echo "✅ Development environment is ready and all checks passed!"
+
+# Additional useful targets
+
+# Watch tests (requires pytest-watch)
+.PHONY: test-watch
+test-watch: sync
+	$(PYTHON) pytest-watch
+
+# Run specific test file
+.PHONY: test-file
+test-file: sync
+	@if [ -z "$(FILE)" ]; then \
+		echo "Usage: make test-file FILE=path/to/test_file.py"; \
+		exit 1; \
+	fi
+	$(PYTHON) pytest $(FILE)
+
+# Coverage report
+.PHONY: coverage
+coverage: sync
+	$(PYTHON) pytest --cov=. --cov-report=html --cov-report=term
+
+# Format check only (no changes)
+.PHONY: format-check
+format-check: sync
+	$(PYTHON) ruff format --check .
+
+# Auto-fix linting issues
+.PHONY: fix
+fix: sync
+	$(PYTHON) ruff check . --fix
+
+# Quick check - faster than 'all' as it runs in parallel
+.PHONY: check
+check: sync
+	@echo "Running all checks in parallel..."
+	@$(MAKE) -j3 test type-check lint-check format-check
diff --git a/src/mcp/client/session_group.py b/src/mcp/client/session_group.py
index a430533b3..a77dc7a1e 100644
--- a/src/mcp/client/session_group.py
+++ b/src/mcp/client/session_group.py
@@ -154,7 +154,6 @@ async def __aexit__(
             for exit_stack in self._session_exit_stacks.values():
                 tg.start_soon(exit_stack.aclose)
 
-
     @property
     def sessions(self) -> list[mcp.ClientSession]:
         """Returns the list of sessions being managed."""