Docs: Update CallToolResult parsing in README (#812)

Co-authored-by: Felix Weinberger <[email protected]>

Author: functicons

README.md

@@ -44,6 +44,7 @@
   - [Advanced Usage](#advanced-usage)
     - [Low-Level Server](#low-level-server)
     - [Writing MCP Clients](#writing-mcp-clients)
+    - [Parsing Tool Results](#parsing-tool-results)
     - [MCP Primitives](#mcp-primitives)
     - [Server Capabilities](#server-capabilities)
   - [Documentation](#documentation)
@@ -1605,6 +1606,75 @@ async def main():
 
 For a complete working example, see [`examples/clients/simple-auth-client/`](examples/clients/simple-auth-client/).
 
+### Parsing Tool Results
+
+When calling tools through MCP, the `CallToolResult` object contains the tool's response in a structured format. Understanding how to parse this result is essential for properly handling tool outputs.
+
+```python
+"""examples/snippets/clients/parsing_tool_results.py"""
+
+import asyncio
+
+from mcp import ClientSession, StdioServerParameters, types
+from mcp.client.stdio import stdio_client
+
+
+async def parse_tool_results():
+    """Demonstrates how to parse different types of content in CallToolResult."""
+    server_params = StdioServerParameters(
+        command="python", args=["path/to/mcp_server.py"]
+    )
+
+    async with stdio_client(server_params) as (read, write):
+        async with ClientSession(read, write) as session:
+            await session.initialize()
+
+            # Example 1: Parsing text content
+            result = await session.call_tool("get_data", {"format": "text"})
+            for content in result.content:
+                if isinstance(content, types.TextContent):
+                    print(f"Text: {content.text}")
+
+            # Example 2: Parsing structured content from JSON tools
+            result = await session.call_tool("get_user", {"id": "123"})
+            if hasattr(result, "structuredContent") and result.structuredContent:
+                # Access structured data directly
+                user_data = result.structuredContent
+                print(f"User: {user_data.get('name')}, Age: {user_data.get('age')}")
+
+            # Example 3: Parsing embedded resources
+            result = await session.call_tool("read_config", {})
+            for content in result.content:
+                if isinstance(content, types.EmbeddedResource):
+                    resource = content.resource
+                    if isinstance(resource, types.TextResourceContents):
+                        print(f"Config from {resource.uri}: {resource.text}")
+                    elif isinstance(resource, types.BlobResourceContents):
+                        print(f"Binary data from {resource.uri}")
+
+            # Example 4: Parsing image content
+            result = await session.call_tool("generate_chart", {"data": [1, 2, 3]})
+            for content in result.content:
+                if isinstance(content, types.ImageContent):
+                    print(f"Image ({content.mimeType}): {len(content.data)} bytes")
+
+            # Example 5: Handling errors
+            result = await session.call_tool("failing_tool", {})
+            if result.isError:
+                print("Tool execution failed!")
+                for content in result.content:
+                    if isinstance(content, types.TextContent):
+                        print(f"Error: {content.text}")
+
+
+async def main():
+    await parse_tool_results()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
 ### MCP Primitives
 
 The MCP protocol defines three core primitives that servers can implement:

examples/snippets/clients/parsing_tool_results.py

@@ -0,0 +1,60 @@
+"""examples/snippets/clients/parsing_tool_results.py"""
+
+import asyncio
+
+from mcp import ClientSession, StdioServerParameters, types
+from mcp.client.stdio import stdio_client
+
+
+async def parse_tool_results():
+    """Demonstrates how to parse different types of content in CallToolResult."""
+    server_params = StdioServerParameters(command="python", args=["path/to/mcp_server.py"])
+
+    async with stdio_client(server_params) as (read, write):
+        async with ClientSession(read, write) as session:
+            await session.initialize()
+
+            # Example 1: Parsing text content
+            result = await session.call_tool("get_data", {"format": "text"})
+            for content in result.content:
+                if isinstance(content, types.TextContent):
+                    print(f"Text: {content.text}")
+
+            # Example 2: Parsing structured content from JSON tools
+            result = await session.call_tool("get_user", {"id": "123"})
+            if hasattr(result, "structuredContent") and result.structuredContent:
+                # Access structured data directly
+                user_data = result.structuredContent
+                print(f"User: {user_data.get('name')}, Age: {user_data.get('age')}")
+
+            # Example 3: Parsing embedded resources
+            result = await session.call_tool("read_config", {})
+            for content in result.content:
+                if isinstance(content, types.EmbeddedResource):
+                    resource = content.resource
+                    if isinstance(resource, types.TextResourceContents):
+                        print(f"Config from {resource.uri}: {resource.text}")
+                    elif isinstance(resource, types.BlobResourceContents):
+                        print(f"Binary data from {resource.uri}")
+
+            # Example 4: Parsing image content
+            result = await session.call_tool("generate_chart", {"data": [1, 2, 3]})
+            for content in result.content:
+                if isinstance(content, types.ImageContent):
+                    print(f"Image ({content.mimeType}): {len(content.data)} bytes")
+
+            # Example 5: Handling errors
+            result = await session.call_tool("failing_tool", {})
+            if result.isError:
+                print("Tool execution failed!")
+                for content in result.content:
+                    if isinstance(content, types.TextContent):
+                        print(f"Error: {content.text}")
+
+
+async def main():
+    await parse_tool_results()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())