Add docs for new thv run --tools-override flag.

docs/toolhive/guides-cli/run-mcp-servers.mdx

@@ -207,6 +207,62 @@ If the server comes from the registry, ToolHive can validate the tool names
 against the list advertised in the image reference. An error is returned in case
 ToolHive cannot find one of the specified tools.
 
+### Override tool names and descriptions
+
+With ToolHive you can modify how tools exposed by an MCP server are exposed to
+clients. In particular, tool names and descriptions can be changed.
+
+This is useful when you want to guide an agent toward calling a specific tool
+for particular questions.
+
+One common use case is running multiple copies of the same MCP server with
+different [network access levels](./network-isolation.mdx)—one for internal
+resources and another for public internet access. By overriding the tool names
+and descriptions, you can help your agent choose the right server for each task.
+
+For example, the `fetch` MCP server exposes a single `fetch` tool with a
+description like:
+
+```
+"Fetches a URL from the internet and optionally extracts its contents as markdown."
+```
+
+To override this, create a configuration file with one entry under
+`toolsOverride` for each tool you want to modify:
+
+```json
+{
+  "toolsOverride": {
+    "fetch": {
+      "name": "toolhive-docs-fetch",
+      "description": "Fetches a URL from https://docs.stacklok.com/toolhive website."
+    }
+  }
+}
+```
+
+Then pass this file to [`thv run`](../reference/cli/thv_run.md):
+
+```sh
+thv run --tools-override override.json fetch
+```
+
+The key in the override object is the _original tool name_, while the `name`
+field contains the _new name_ that clients will see.
+
+:::info
+
+Take care when using `--tools` and `--tools-override` together in the same
+command.
+
+Tool filtering and tool overrides work independently: filtering limits access to
+a subset of tools, while overrides change how those tools appear to clients.
+
+When using both options, `--tools` must reference the _overridden names_ (the
+new names you define) since those are what clients will see.
+
+:::
+
 ## Run a custom MCP server
 
 To run an MCP server that isn't in the registry, you can use a