[MCP] Add configuration options to enable or disable specific tools (#5367)

Some MCP servers expose a lot of tools. In those cases, it is reasonable
to allow/denylist tools for Codex to use so it doesn't get overwhelmed
with too many tools.

The new configuration options available in the `mcp_server` toml table
are:
* `enabled_tools`
* `disabled_tools`

Fixes #4796

codex-rs/cli/src/mcp_cmd.rs

@@ -253,6 +253,8 @@ async fn run_add(config_overrides: &CliConfigOverrides, add_args: AddArgs) -> Re
         enabled: true,
         startup_timeout_sec: None,
         tool_timeout_sec: None,
+        enabled_tools: None,
+        disabled_tools: None,
     };
 
     servers.insert(name.clone(), new_entry);
@@ -676,6 +678,8 @@ async fn run_get(config_overrides: &CliConfigOverrides, get_args: GetArgs) -> Re
             "name": get_args.name,
             "enabled": server.enabled,
             "transport": transport,
+            "enabled_tools": server.enabled_tools.clone(),
+            "disabled_tools": server.disabled_tools.clone(),
             "startup_timeout_sec": server
                 .startup_timeout_sec
                 .map(|timeout| timeout.as_secs_f64()),
@@ -687,8 +691,28 @@ async fn run_get(config_overrides: &CliConfigOverrides, get_args: GetArgs) -> Re
         return Ok(());
     }
 
+    if !server.enabled {
+        println!("{} (disabled)", get_args.name);
+        return Ok(());
+    }
+
     println!("{}", get_args.name);
     println!("  enabled: {}", server.enabled);
+    let format_tool_list = |tools: &Option<Vec<String>>| -> String {
+        match tools {
+            Some(list) if list.is_empty() => "[]".to_string(),
+            Some(list) => list.join(", "),
+            None => "-".to_string(),
+        }
+    };
+    if server.enabled_tools.is_some() {
+        let enabled_tools_display = format_tool_list(&server.enabled_tools);
+        println!("  enabled_tools: {enabled_tools_display}");
+    }
+    if server.disabled_tools.is_some() {
+        let disabled_tools_display = format_tool_list(&server.disabled_tools);
+        println!("  disabled_tools: {disabled_tools_display}");
+    }
     match &server.transport {
         McpServerTransportConfig::Stdio {
             command,

codex-rs/cli/tests/mcp_list.rs

@@ -134,3 +134,28 @@ async fn list_and_get_render_expected_output() -> Result<()> {
 
     Ok(())
 }
+
+#[tokio::test]
+async fn get_disabled_server_shows_single_line() -> Result<()> {
+    let codex_home = TempDir::new()?;
+
+    let mut add = codex_command(codex_home.path())?;
+    add.args(["mcp", "add", "docs", "--", "docs-server"])
+        .assert()
+        .success();
+
+    let mut servers = load_global_mcp_servers(codex_home.path()).await?;
+    let docs = servers
+        .get_mut("docs")
+        .expect("docs server should exist after add");
+    docs.enabled = false;
+    write_global_mcp_servers(codex_home.path(), &servers)?;
+
+    let mut get_cmd = codex_command(codex_home.path())?;
+    let get_output = get_cmd.args(["mcp", "get", "docs"]).output()?;
+    assert!(get_output.status.success());
+    let stdout = String::from_utf8(get_output.stdout)?;
+    assert_eq!(stdout.trim_end(), "docs (disabled)");
+
+    Ok(())
+}