Fix readme and user guide (#105)

Signed-off-by: Nathalie Jonathan <[email protected]>

Author: nathaliellenaa

README.md

@@ -47,7 +47,7 @@ Core tools are grouped under the `core_tools` category and can be disabled at on
 - [MsearchTool](https://docs.opensearch.org/docs/latest/api-reference/search-apis/multi-search/): Allows to execute several search operations in one request.
 
 ### Additional Tools (Disabled by Default)
-The following tools are available but disabled by default. To enable them, see the [Tool Filtering](USER_GUIDE.md#tool-filtering) section in the User Guide.
+The following tools are available but disabled by default. To enable them, see the [Tool Filter](USER_GUIDE.md#tool-filter) section in the User Guide.
 
 - [GetClusterStateTool](https://docs.opensearch.org/docs/latest/api-reference/cluster-api/cluster-state/): Gets the current state of the cluster including node information, index settings, and more.
 - [GetSegmentsTool](https://docs.opensearch.org/docs/latest/api-reference/cat/cat-segments/): Gets information about Lucene segments in indices, including memory usage, document counts, and segment sizes.

USER_GUIDE.md

@@ -540,6 +540,8 @@ tools:
   ListIndexTool:
     display_name: "Index_Manager"
     description: "List and manage OpenSearch indices"
+    args:
+      index: "Custom description for the 'index' argument in ListIndexTool."
   GetShardsTool:
     description: "Retrieve detailed information about OpenSearch shards"
 ```
@@ -553,18 +555,18 @@ python -m mcp_server_opensearch --config path/to/config.yml
 
 Customize tools directly via command line arguments:
 ```bash
-python -m mcp_server_opensearch --tool.ListIndexTool.display_name="Index_Manager" --tool.SearchIndexTool.description="Custom search tool"
+python -m mcp_server_opensearch --tool.ListIndexTool.display_name="Index_Manager" --tool.SearchIndexTool.description="Custom search tool" --tool.GetShardsTool.args.index.description="Custom description" 
 ```
 
 ### Priority
 
-Runtime parameters have higher priority than configuration file settings. If both are provided, runtime parameters will override the corresponding values in the configuration file.
+Configuration file settings have higher priority than runtime parameters. If both are provided, configuration file settings will override the corresponding values in the runtime parameters.
 
 ### Important Notes
 - Tool customization is available in both single and multi modes
 - Only existing tools can be customized; new tools cannot be created
 - Changes take effect immediately when the server starts
-- Invalid tool names or properties will be ignored
+- Invalid tool names or properties will throw an error
 
 ## LangChain Integration