refactor: McpError renamed to MCPError and flatten parameters (#1956)

Co-authored-by: Max Isbey <224885523+maxisbey@users.noreply.github.com>

docs/experimental/tasks-client.md

@@ -337,7 +337,7 @@ if __name__ == "__main__":
 Handle task errors gracefully:
 
 ```python
-from mcp.shared.exceptions import McpError
+from mcp.shared.exceptions import MCPError
 
 try:
     result = await session.experimental.call_tool_as_task("my_tool", args)
@@ -349,8 +349,8 @@ try:
 
     final = await session.experimental.get_task_result(task_id, CallToolResult)
 
-except McpError as e:
-    print(f"MCP error: {e.error.message}")
+except MCPError as e:
+    print(f"MCP error: {e.message}")
 except Exception as e:
     print(f"Error: {e}")
 ```

docs/migration.md

@@ -121,6 +121,38 @@ result = await session.list_resources(params=PaginatedRequestParams(cursor="next
 result = await session.list_tools(params=PaginatedRequestParams(cursor="next_page_token"))
 ```
 
+### `McpError` renamed to `MCPError`
+
+The `McpError` exception class has been renamed to `MCPError` for consistent naming with the MCP acronym style used throughout the SDK.
+
+**Before (v1):**
+
+```python
+from mcp.shared.exceptions import McpError
+
+try:
+    result = await session.call_tool("my_tool")
+except McpError as e:
+    print(f"Error: {e.error.message}")
+```
+
+**After (v2):**
+
+```python
+from mcp.shared.exceptions import MCPError
+
+try:
+    result = await session.call_tool("my_tool")
+except MCPError as e:
+    print(f"Error: {e.message}")
+```
+
+`MCPError` is also exported from the top-level `mcp` package:
+
+```python
+from mcp import MCPError
+```
+
 ### `FastMCP` renamed to `MCPServer`
 
 The `FastMCP` class has been renamed to `MCPServer` to better reflect its role as the main server class in the SDK. This is a simple rename with no functional changes to the class itself.