diff --git a/README.ko.md b/README.ko.md
index b652182..db86b9f 100644
--- a/README.ko.md
+++ b/README.ko.md
@@ -561,19 +561,21 @@ Google Gemini 모델을 위한 내장 Antigravity OAuth를 활성화합니다:
 
 ### OmO Agent
 
-기본 OmO 에이전트 동작을 설정합니다:
+OmO는 기본적으로 활성화되며, 기본 primary 에이전트가 됩니다. 내장 "build" 에이전트를 대체하면서 `builtIn` 플래그를 유지하여, OmO가 에이전트 목록에서 첫 번째로 표시됩니다.
+
+OmO를 비활성화하고 원래 build 에이전트를 복원하려면:
 
 ```json
 {
   "omo_agent": {
-    "disable_build": true
+    "disabled": true
   }
 }
 ```
 
 | 옵션 | 기본값 | 설명 |
 |------|--------|------|
-| `disable_build` | `true` | `true`면 기본 Build 에이전트를 숨깁니다. OmO가 유일한 primary 에이전트가 됩니다. `false`로 설정하면 Build 에이전트가 OmO와 함께 표시됩니다. |
+| `disabled` | `false` | `true`면 OmO를 비활성화하고 원래 build 에이전트를 복원합니다. `false`(기본값)면 OmO가 build 에이전트를 대체하여 기본 primary 에이전트가 됩니다. |
 
 ### Hooks
 
diff --git a/README.md b/README.md
index bd8cabf..959b1d7 100644
--- a/README.md
+++ b/README.md
@@ -562,19 +562,21 @@ Available agents: `oracle`, `librarian`, `explore`, `frontend-ui-ux-engineer`, `
 
 ### OmO Agent
 
-Configure the default OmO agent behavior:
+OmO is enabled by default and becomes the default primary agent. It replaces the built-in "build" agent while keeping the `builtIn` flag, ensuring OmO appears first in the agent list.
+
+To disable OmO and restore the original build agent:
 
 ```json
 {
   "omo_agent": {
-    "disable_build": true
+    "disabled": true
   }
 }
 ```
 
 | Option | Default | Description |
 |--------|---------|-------------|
-| `disable_build` | `true` | When `true`, hides the default Build agent. OmO becomes the only primary agent. Set to `false` to show Build agent alongside OmO. |
+| `disabled` | `false` | When `true`, disables OmO and restores the original build agent. When `false` (default), OmO replaces the build agent as the default primary agent. |
 
 ### Hooks
 
diff --git a/src/agents/omo.ts b/src/agents/omo.ts
index 4094294..932488a 100644
--- a/src/agents/omo.ts
+++ b/src/agents/omo.ts
@@ -366,41 +366,6 @@ export const omoAgent: AgentConfig = {
     budgetTokens: 32000,
   },
   maxTokens: 128000,
-  tools: {
-    read: true,
-    write: true,
-    edit: true,
-    multiedit: true,
-    patch: true,
-    glob: true,
-    grep: true,
-    list: true,
-    bash: true,
-    batch: true,
-    webfetch: true,
-    websearch: true,
-    codesearch: true,
-    todowrite: true,
-    todoread: true,
-    task: true,
-    lsp_hover: true,
-    lsp_goto_definition: true,
-    lsp_find_references: true,
-    lsp_document_symbols: true,
-    lsp_workspace_symbols: true,
-    lsp_diagnostics: true,
-    lsp_rename: true,
-    lsp_prepare_rename: true,
-    lsp_code_actions: true,
-    lsp_code_action_resolve: true,
-    lsp_servers: true,
-    ast_grep_search: true,
-    ast_grep_replace: true,
-    skill: true,
-    call_omo_agent: true,
-    background_task: true,
-    background_output: true,
-  },
   prompt: OMO_SYSTEM_PROMPT,
   color: "#00CED1",
 }
diff --git a/src/config/schema.ts b/src/config/schema.ts
index 1beea29..bc839c6 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -96,7 +96,7 @@ export const ClaudeCodeConfigSchema = z.object({
 })
 
 export const OmoAgentConfigSchema = z.object({
-  disable_build: z.boolean().optional(),
+  disabled: z.boolean().optional(),
 })
 
 export const OhMyOpenCodeConfigSchema = z.object({
diff --git a/src/index.ts b/src/index.ts
index 12279f0..751184f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -279,15 +279,32 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
       const userAgents = (pluginConfig.claude_code?.agents ?? true) ? loadUserAgents() : {};
       const projectAgents = (pluginConfig.claude_code?.agents ?? true) ? loadProjectAgents() : {};
 
-      const shouldHideBuild = pluginConfig.omo_agent?.disable_build !== false;
+      const isOmoEnabled = pluginConfig.omo_agent?.disabled !== true;
 
-      config.agent = {
-        ...builtinAgents,
-        ...userAgents,
-        ...projectAgents,
-        ...config.agent,
-        ...(shouldHideBuild ? { build: { mode: "subagent" } } : {}),
-      };
+      if (isOmoEnabled && builtinAgents.OmO) {
+        // TODO: When OpenCode releases `default_agent` config option (PR #5313),
+        // remove this hack and use `config.default_agent = "OmO"` instead.
+        // This hack works by:
+        // 1. Setting build agent's display name to "OmO" (builtIn: true, appears first in TUI)
+        // 2. Adding OmO as a subagent (actual execution target when "OmO" is selected)
+        // Tracking: https://github.com/sst/opencode/pull/5313
+        const { OmO: omoConfig, ...restAgents } = builtinAgents;
+        config.agent = {
+          ...restAgents,
+          ...userAgents,
+          ...projectAgents,
+          ...config.agent,
+          build: { ...omoConfig, name: "OmO" },
+          OmO: { ...omoConfig, mode: "subagent" },
+        };
+      } else {
+        config.agent = {
+          ...builtinAgents,
+          ...userAgents,
+          ...projectAgents,
+          ...config.agent,
+        };
+      }
 
       config.tools = {
         ...config.tools,