diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0cee99f..e00f09d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -2,6 +2,23 @@
 
 We'd love to accept your patches and contributions to this project.
 
+## Table of Contents
+
+- [Before you begin](#before-you-begin)  
+  - [Sign our Contributor License Agreement](#sign-our-contributor-license-agreement)  
+  - [Review our community guidelines](#review-our-community-guidelines)
+- [Contribution workflow](#contribution-workflow)  
+  - [Finding Issues to Work On](#finding-issues-to-work-on)  
+  - [Requirement for PRs](#requirement-for-prs)  
+  - [Large or Complex Changes](#large-or-complex-changes)  
+  - [Testing Requirements](#testing-requirements)  
+  - [Unit Tests](#unit-tests)  
+  - [End-to-End (E2E) Tests](#manual-end-to-end-e2e-tests)  
+  - [Documentation](#documentation)  
+  - [Development Setup](#development-setup)  
+- [Code reviews](#code-reviews)
+
+  
 ## Before you begin
 
 ### Sign our Contributor License Agreement
@@ -23,7 +40,68 @@ sign a new one.
 This project follows
 [Google's Open Source Community Guidelines](https://opensource.google/conduct/).
 
-## Contribution process
+## Contribution workflow
+
+### Finding Issues to Work On
+
+- Browse issues labeled **`good first issue`** (newcomer-friendly) or **`help wanted`** (general contributions).  
+- For other issues, please kindly ask before contributing to avoid duplication.
+
+
+### Requirement for PRs
+
+- All PRs, other than small documentation or typo fixes, should have a Issue assoicated. If not, please create one. 
+- Small, focused PRs. Keep changes minimal—one concern per PR.
+- For bug fixes or features, please provide logs or screenshot after the fix is applied to help reviewers better understand the fix.
+- Please include a `testing plan` section in your PR to talk about how you will test. This will save time for PR review. See `Testing Requirements` section for more details.
+
+### Large or Complex Changes
+For substantial features or architectural revisions:
+
+- Open an Issue First: Outline your proposal, including design considerations and impact.
+- Gather Feedback: Discuss with maintainers and the community to ensure alignment and avoid duplicate work
+
+### Testing Requirements
+
+To maintain code quality and prevent regressions, all code changes must include comprehensive tests and verifiable end-to-end (E2E) evidence.
+
+
+#### Unit Tests
+
+Please add or update unit tests for your change. Please include a summary of passed `pytest` results.
+
+Requirements for unit tests:
+
+- **Coverage:** Cover new features, edge cases, error conditions, and typical use cases.  
+- **Location:** Add or update tests under `tests/unittests/`, following existing naming conventions (e.g., `test_<module>_<feature>.py`).  
+- **Framework:** Use `pytest`. Tests should be:  
+  - Fast and isolated.  
+  - Written clearly with descriptive names.  
+  - Free of external dependencies (use mocks or fixtures as needed).  
+- **Quality:** Aim for high readability and maintainability; include docstrings or comments for complex scenarios.
+
+#### Manual End-to-End (E2E) Tests
+
+Manual E2E tests ensure integrated flows work as intended. Your tests should cover all scenarios. Sometimes, it's also good to ensure relevant functionality is not impacted.
+
+Depending on your change:
+
+- **ADK Web:**  
+  - Use the `adk web` to verify functionality.  
+  - Capture and attach relevant screenshots demonstrating the UI/UX changes or outputs.  
+  - Label screenshots clearly in your PR description.
+
+- **Runner:**
+  - Provide the testing setup. For example, the agent definition, and the runner setup.
+  - Execute the `runner` tool to reproduce workflows.  
+  - Include the command used and console output showing test results.  
+  - Highlight sections of the log that directly relate to your change.
+
+### Documentation
+
+For any changes that impact user-facing documentation (guides, API reference, tutorials), please open a PR in the [adk-docs](https://github.com/google/adk-docs) repository to update relevant part before or alongside your code PR.
+
+### Development Setup
 1.  **Clone the repository:**
 
     ```shell
@@ -53,21 +131,8 @@ This project follows
     ```shell
     uv run pyink  --config pyproject.toml ./src
     ```
-
-### Requirement for PRs
-
-- All PRs, other than small documentation or typo fixes, should have a Issue assoicated. If not, please create one. 
-- Small, focused PRs. Keep changes minimal—one concern per PR.
-- For bug fixes or features, please provide logs or screenshot after the fix is applied to help reviewers better understand the fix.
-- Please add corresponding testing for your code change if it's not covered by existing tests.
-
-### Large or Complex Changes
-For substantial features or architectural revisions:
-
-- Open an Issue First: Outline your proposal, including design considerations and impact.
-- Gather Feedback: Discuss with maintainers and the community to ensure alignment and avoid duplicate work
-
-### Code reviews
+    
+## Code reviews
 
 All submissions, including submissions by project members, require review. We
 use GitHub pull requests for this purpose. Consult