docs: Fix typos, broken links, and grammar across documentation

Merge https://github.com/google/adk-python/pull/3937

**Please ensure you have read the [contribution guide](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) before creating a pull request.**

### Link to Issue or Description of Change
Not applicable

**Problem:**
Several markdown files contained typos, grammatical errors (e.g., "search youtubes"), and awkward phrasing.
**Solution:**
Performed a comprehensive quality assurance pass on the documentation.
- Fixed typos in README.md and AGENTS.md.
- Improved grammar and phrasing in CONTRIBUTING.md and sample READMEs.

### Testing Plan

This is a documentation and typo fix PR.

**Unit Tests:**

- [ ] I have added or updated unit tests for my change.
- [ ] All unit tests pass locally.
N/A - Documentation changes only.

**Manual End-to-End (E2E) Tests:**

This is a documentation and typo fix PR.

### Checklist

- [x] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document.
- [x] I have performed a self-review of my own code.
- [ ] I have commented my code, particularly in hard-to-understand areas.
- [ ] I have added tests that prove my fix is effective or that my feature works.
- [ ] New and existing unit tests pass locally with my changes.
- [x] I have manually tested my changes end-to-end.
- [ ] Any dependent changes have been merged and published in downstream modules.

Co-authored-by: Xiang (Sean) Zhou <seanzhougoogle@google.com>
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/3937 from Goodnight77:docs/fix-typos a0cf4db6741f19c77eeb0746c9db524dd02121ac
PiperOrigin-RevId: 845599254

CHANGELOG.md

@@ -4,7 +4,7 @@
 
 ### Features
 * **[Interactions API Support]**
-  * The newly released Gemini [Interactions API](https://ai.google.dev/gemini-api/docs/interactions) is supported in ADK Now. To use it:
+  * The newly released Gemini [Interactions API](https://ai.google.dev/gemini-api/docs/interactions) is supported in ADK now. To use it:
   ```Python
   Agent(
     model=Gemini(
@@ -352,7 +352,7 @@
 
 * Returns dict as result from McpTool to comply with BaseTool expectations ([4df9263](https://github.com/google/adk-python/commit/4df926388b6e9ebcf517fbacf2f5532fd73b0f71))
 * Fixes the identity prompt to be one line ([7d5c6b9](https://github.com/google/adk-python/commit/7d5c6b9acf0721dd230f08df919c7409eed2b7d0))
-* Fix the broken langchain importing caused their 1.0.0 release ([c850da3](https://github.com/google/adk-python/commit/c850da3a07ec1441037ced1b654d8aacacd277ab))
+* Fix the broken langchain importing caused by their 1.0.0 release ([c850da3](https://github.com/google/adk-python/commit/c850da3a07ec1441037ced1b654d8aacacd277ab))
 * Fix BuiltInCodeExecutor to support visualizations ([ce3418a](https://github.com/google/adk-python/commit/ce3418a69de56570847d45f56ffe7139ab0a47aa))
 * Relax runner app-name enforcement and improve agent origin inference ([dc4975d](https://github.com/google/adk-python/commit/dc4975dea9fb79ad887460659f8f397a537ee38f))
 * Improve error message when adk web is run in wrong directory ([4a842c5](https://github.com/google/adk-python/commit/4a842c5a1334c3ee01406f796651299589fe12ab))
@@ -629,7 +629,7 @@
 ### Documentation
 
 * Clean up docs in sample [a360bc2](https://github.com/google/adk-python/commit/a360bc25429bf4bef6a80da59afe30d6933a844b)
-* Fixes root_agent.yaml in tool_mcp_stdio_notion_config for Agent Config sample and add README.md [2c088ac](https://github.com/google/adk-python/commit/2c088acc9b34f030537b02b45a4afd458445d15b)
+* Fixes root_agent.yaml in tool_mcp_stdio_notion_config for Agent Config sample and adds README.md [2c088ac](https://github.com/google/adk-python/commit/2c088acc9b34f030537b02b45a4afd458445d15b)
 * Add What's new section to README.md [ccab076](https://github.com/google/adk-python/commit/ccab076aceff917591eb3a3cc89a9f85226b832a)
 
 ## 1.12.0 (2025-08-21)

CONTRIBUTING.md

@@ -56,14 +56,14 @@ information on using pull requests.
 
 ### Requirement for PRs
 
--   All PRs, other than small documentation or typo fixes, should have a Issue
+-   All PRs, other than small documentation or typo fixes, should have an Issue
     associated. If a relevant issue doesn't exist, please create one first or
     you may instead describe the bug or feature directly within the PR
     description, following the structure of our issue templates.
 -   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
+-   Please include a `testing plan` section in your PR to describe how you
     will test. This will save time for PR review. See `Testing Requirements`
     section for more details.
 
@@ -126,7 +126,7 @@ Depending on your change:
 
 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
+[adk-docs](https://github.com/google/adk-docs) repository to update the relevant
 part before or alongside your code PR.
 
 ## Development Setup
@@ -160,7 +160,11 @@ part before or alongside your code PR.
     source .venv/bin/activate
     ```
 
-    **windows** `shell source .\.venv\Scripts\activate`
+    **Windows**
+
+    ```shell
+    source .\.venv\Scripts\activate
+    ```
 
 4.  **Install dependencies:**
 
@@ -230,7 +234,7 @@ part before or alongside your code PR.
 ## Contributing Resources
 
 [Contributing folder](https://github.com/google/adk-python/tree/main/contributing)
-has resources that is helpful for contributors.
+has resources that are helpful for contributors.
 
 ## Vibe Coding
 

README.md

@@ -164,7 +164,7 @@ of the ADK.
 
 ## Vibe Coding
 
-If you are to develop agent via vibe coding the [llms.txt](./llms.txt) and the [llms-full.txt](./llms-full.txt) can be used as context to LLM. While the former one is a summarized one and the later one has the full information in case your LLM has big enough context window.
+If you want to develop agent via vibe coding the [llms.txt](./llms.txt) and the [llms-full.txt](./llms-full.txt) can be used as context to LLM. While the former one is a summarized one and the later one has the full information in case your LLM has big enough context window.
 
 ## Community Events
 

contributing/README.md

@@ -1,6 +1,6 @@
 # Contributing Resources
 
-This folder host resources for ADK contributors, for example, testing samples etc.
+This folder hosts resources for ADK contributors, for example, testing samples etc.
 
 ## Samples
 
@@ -13,4 +13,4 @@ Samples folder host samples to test different features. The samples are usually
 The [adk_project_overview_and_architecture.md](adk_project_overview_and_architecture.md) describes the ADK project overview and its technical architecture from high-level.
 
 This is helpful for contributors to understand the project and design philosophy.
- It can also be feed into LLMs for vibe-coding.
+ It can also be fed into LLMs for vibe-coding.

contributing/adk_project_overview_and_architecture.md

@@ -34,7 +34,7 @@ my_adk_project/
     └── my_app/
         ├── agents/
         │   ├── my_agent/
-        │   │   ├── __init__.py   # Must contain: from. import agent \
+        │   │   ├── __init__.py   # Must contain: from . import agent \
         │   │   └── agent.py      # Must contain: root_agent = Agent(...) \
         │   └── another_agent/
         │       ├── __init__.py
@@ -43,7 +43,7 @@ my_adk_project/
 
 agent.py: Must define the agent and assign it to a variable named root_agent. This is how ADK's tools find it.
 
-`__init__.py`: In each agent directory, it must contain from. import agent to make the agent discoverable.
+`__init__.py`: In each agent directory, it must contain `from . import agent` to make the agent discoverable.
 
 ## Local Development & Debugging
 
@@ -69,7 +69,7 @@ We expose agents as production APIs using FastAPI.
 
 - Custom Endpoints: We can add our own routes (e.g., /health) to the app object returned by the helper.
 
-Python
+```Python
 
 from google.adk.cli.fast_api import get_fast_api_app
 app = get_fast_api_app(agent_dir="./agents")
@@ -77,6 +77,7 @@ app = get_fast_api_app(agent_dir="./agents")
 @app.get("/health")
 async def health_check():
     return {"status": "ok"}
+```
 
 
 ## Deployment to Production

contributing/samples/bigtable/README.md

@@ -72,7 +72,7 @@ type.
 
 1.  Follow https://developers.google.com/workspace/guides/configure-oauth-consent
     to add scope "https://www.googleapis.com/auth/bigtable.admin" and
-    "https://www.googleapis.com/auth/bigtable.data" as declaration, this is used
+    "https://www.googleapis.com/auth/bigtable.data" as a declaration, this is used
     for review purpose.
 
 1.  Follow

contributing/samples/langchain_youtube_search_agent/README.md

@@ -1,7 +1,7 @@
 # Langchain YouTube Search Agent
 
-This agent utilize the Langchain YoutubeSearchTool to search youtubes.
-You need to install below dependencies:
+This agent utilizes the Langchain YoutubeSearchTool to search Youtube Videos.
+You need to install the following dependencies:
 
 ```python
 uv pip install youtube_search

contributing/samples/live_bidi_streaming_single_agent/readme.md

@@ -8,7 +8,7 @@ Follow these steps to get the agent up and running:
 
 1.  **Start the ADK Web Server**
     Open your terminal, navigate to the root directory that contains the 
-    `live_bidi_streaming_agent` folder, and execute the following command:
+    `live_bidi_streaming_single_agent` folder, and execute the following command:
     ```bash
     adk web
     ```

contributing/samples/mcp_streamablehttp_agent/README.md

@@ -1,6 +1,6 @@
 This agent connects to a local MCP server via Streamable HTTP.
 
-To run this agent, start the local MCP server first by :
+To run this agent, start the local MCP server first by:
 
 ```bash
 uv run filesystem_server.py