docs: Fixes root_agent.yaml in tool_mcp_stdio_notion_config for Agent Config sample and add README.md

PiperOrigin-RevId: 798241478

Author: Jacksunwei

contributing/samples/tool_mcp_stdio_notion_config/README.md

@@ -0,0 +1,48 @@
+# Config-based Agent Sample - MCP Toolset with Notion MCP Server
+
+This sample demonstrates how to configure an ADK agent to use the Notion MCP server for interacting with Notion pages and databases.
+
+## Setup Instructions
+
+### 1. Create a Notion Integration
+
+1. Go to [Notion Integrations](https://www.notion.so/my-integrations)
+2. Click "New integration"
+3. Give it a name and select your workspace
+4. Copy the "Internal Integration Secret" (starts with `ntn_`)
+
+For detailed setup instructions, see the [Notion MCP Server documentation](https://www.npmjs.com/package/@notionhq/notion-mcp-server).
+
+### 2. Configure the Agent
+
+Replace `<your_notion_token>` in `root_agent.yaml` with your actual Notion integration token:
+
+```yaml
+env:
+  OPENAPI_MCP_HEADERS: '{"Authorization": "Bearer secret_your_actual_token_here", "Notion-Version": "2022-06-28"}'
+```
+
+### 3. Grant Integration Access
+
+**Important**: After creating the integration, you must grant it access to specific pages and databases:
+
+1. Go to `Access` tab in [Notion Integrations](https://www.notion.so/my-integrations) page
+2. Click "Edit access"
+3. Add pages or databases as needed
+
+### 4. Run the Agent
+
+Use the `adk web` to run the agent and interact with your Notion workspace.
+
+## Example Queries
+
+- "What can you do for me?"
+- "Search for 'project' in my pages"
+- "Create a new page called 'Meeting Notes'"
+- "List all my databases"
+
+## Troubleshooting
+
+- If you get "Unauthorized" errors, check that your token is correct
+- If you get "Object not found" errors, ensure you've granted the integration access to the specific pages/databases
+- Make sure the Notion API version in the headers matches what the MCP server expects

contributing/samples/tool_mcp_stdio_notion_config/root_agent.yaml

@@ -13,4 +13,4 @@ tools:
       - "-y"
       - "@notionhq/notion-mcp-server"
       env:
-        OPENAPI_MCP_HEADERS: "{'Authorization': 'Bearer fake_notion_api_key', 'Notion-Version': '2022-06-28'}"
+        OPENAPI_MCP_HEADERS: '{"Authorization": "Bearer <your_notion_token>", "Notion-Version": "2022-06-28"}'