diff --git a/examples/01_standalone_sdk/25_agent_delegation.py b/examples/01_standalone_sdk/25_agent_delegation.py
index 23532c2944..e5d9188ddd 100644
--- a/examples/01_standalone_sdk/25_agent_delegation.py
+++ b/examples/01_standalone_sdk/25_agent_delegation.py
@@ -9,8 +9,6 @@
 
 import os
 
-from pydantic import SecretStr
-
 from openhands.sdk import (
     LLM,
     Agent,
@@ -26,7 +24,7 @@
     DelegateTool,
     DelegationVisualizer,
 )
-from openhands.tools.preset.default import get_default_tools
+from openhands.tools.preset.default import get_default_tools, register_builtins_agents
 
 
 ONLY_RUN_SIMPLE_DELEGATION = False
@@ -34,22 +32,18 @@
 logger = get_logger(__name__)
 
 # Configure LLM and agent
-# You can get an API key from https://app.all-hands.dev/settings/api-keys
-api_key = os.getenv("LLM_API_KEY")
-assert api_key is not None, "LLM_API_KEY environment variable is not set."
-model = os.getenv("LLM_MODEL", "anthropic/claude-sonnet-4-5-20250929")
 llm = LLM(
-    model=model,
-    api_key=SecretStr(api_key),
+    model=os.getenv("LLM_MODEL", "anthropic/claude-sonnet-4-5-20250929"),
+    api_key=os.getenv("LLM_API_KEY"),
     base_url=os.environ.get("LLM_BASE_URL", None),
     usage_id="agent",
 )
 
 cwd = os.getcwd()
 
-register_tool("DelegateTool", DelegateTool)
-tools = get_default_tools(enable_browser=False)
-tools.append(Tool(name="DelegateTool"))
+tools = get_default_tools(enable_browser=True)
+tools.append(Tool(name=DelegateTool.name))
+register_builtins_agents()
 
 main_agent = Agent(
     llm=llm,
@@ -61,7 +55,7 @@
     visualizer=DelegationVisualizer(name="Delegator"),
 )
 
-task_message = (
+conversation.send_message(
     "Forget about coding. Let's switch to travel planning. "
     "Let's plan a trip to London. I have two issues I need to solve: "
     "Lodging: what are the best areas to stay at while keeping budget in mind? "
@@ -72,7 +66,6 @@
     "They should keep it short. After getting the results, merge both analyses "
     "into a single consolidated report.\n\n"
 )
-conversation.send_message(task_message)
 conversation.run()
 
 conversation.send_message(
@@ -81,18 +74,57 @@
 conversation.run()
 
 # Report cost for simple delegation example
-cost_1 = conversation.conversation_stats.get_combined_metrics().accumulated_cost
-print(f"EXAMPLE_COST (simple delegation): {cost_1}")
+cost_simple = conversation.conversation_stats.get_combined_metrics().accumulated_cost
+print(f"EXAMPLE_COST (simple delegation): {cost_simple}")
 
 print("Simple delegation example done!", "\n" * 20)
 
-
-# -------- Agent Delegation Second Part: User-Defined Agent Types --------
-
 if ONLY_RUN_SIMPLE_DELEGATION:
+    # For CI: always emit the EXAMPLE_COST marker before exiting.
+    print(f"EXAMPLE_COST: {cost_simple}")
     exit(0)
 
 
+# -------- Agent Delegation Second Part: Built-in Agent Types (Explore + Bash) --------
+
+main_agent = Agent(
+    llm=llm,
+    tools=[Tool(name=DelegateTool.name)],
+)
+conversation = Conversation(
+    agent=main_agent,
+    workspace=cwd,
+    visualizer=DelegationVisualizer(name="Delegator (builtins)"),
+)
+
+builtin_task_message = (
+    "Demonstrate SDK built-in sub-agent types. "
+    "1) Spawn an 'explore' sub-agent and ask it to list the markdown files in "
+    "openhands-sdk/openhands/sdk/subagent/builtins/ and summarize what each "
+    "built-in agent type is for (based on the file contents). "
+    "2) Spawn a 'bash' sub-agent and ask it to run `python --version` in the "
+    "terminal and return the exact output. "
+    "3) Merge both results into a short report. "
+    "Do not use internet access."
+)
+
+print("=" * 100)
+print("Demonstrating built-in agent delegation (explore + bash)...")
+print("=" * 100)
+
+conversation.send_message(builtin_task_message)
+conversation.run()
+
+# Report cost for builtin agent types example
+cost_builtin = conversation.conversation_stats.get_combined_metrics().accumulated_cost
+print(f"EXAMPLE_COST (builtin agents): {cost_builtin}")
+
+print("Built-in agent delegation example done!", "\n" * 20)
+
+
+# -------- Agent Delegation Third Part: User-Defined Agent Types --------
+
+
 def create_lodging_planner(llm: LLM) -> Agent:
     """Create a lodging planner focused on London stays."""
     skills = [
@@ -190,10 +222,12 @@ def create_activities_planner(llm: LLM) -> Agent:
 conversation.run()
 
 # Report cost for user-defined agent types example
-cost_2 = conversation.conversation_stats.get_combined_metrics().accumulated_cost
-print(f"EXAMPLE_COST (user-defined agents): {cost_2}")
+cost_user_defined = (
+    conversation.conversation_stats.get_combined_metrics().accumulated_cost
+)
+print(f"EXAMPLE_COST (user-defined agents): {cost_user_defined}")
 
 print("All done!")
 
 # Full example cost report for CI workflow
-print(f"EXAMPLE_COST: {cost_1 + cost_2}")
+print(f"EXAMPLE_COST: {cost_simple + cost_builtin + cost_user_defined}")
diff --git a/openhands-sdk/openhands/sdk/conversation/impl/local_conversation.py b/openhands-sdk/openhands/sdk/conversation/impl/local_conversation.py
index b83cfabcb5..229c023955 100644
--- a/openhands-sdk/openhands/sdk/conversation/impl/local_conversation.py
+++ b/openhands-sdk/openhands/sdk/conversation/impl/local_conversation.py
@@ -51,7 +51,6 @@
     register_file_agents,
     register_plugin_agents,
 )
-from openhands.sdk.subagent.registry import register_builtins_agents
 from openhands.sdk.tool.schema import Action, Observation
 from openhands.sdk.utils.cipher import Cipher
 from openhands.sdk.workspace import LocalWorkspace
@@ -417,12 +416,9 @@ def _register_file_based_agents(self) -> None:
                 then `{project}/.openhands/agents/*.md`)
           4. User-level file agents (`~/.agents/agents/*.md`,
                 then `~/.openhands/agents/*.md`)
-          5. SDK builtin agents (`subagent/builtins/*.md`)
         """
         # register project-level and then user-level file-based agents
         register_file_agents(self.workspace.working_dir)
-        # register builtins agents
-        register_builtins_agents()
 
     def _ensure_agent_ready(self) -> None:
         """Ensure the agent is fully initialized with plugins and agents loaded.
diff --git a/openhands-sdk/openhands/sdk/subagent/registry.py b/openhands-sdk/openhands/sdk/subagent/registry.py
index ae5ecc13cc..e345d84a56 100644
--- a/openhands-sdk/openhands/sdk/subagent/registry.py
+++ b/openhands-sdk/openhands/sdk/subagent/registry.py
@@ -30,7 +30,6 @@ def create_security_expert(llm):
 
 from openhands.sdk.logger import get_logger
 from openhands.sdk.subagent.load import (
-    load_agents_from_dir,
     load_project_agents,
     load_user_agents,
 )
@@ -43,8 +42,6 @@ def create_security_expert(llm):
 
 logger = get_logger(__name__)
 
-BUILTINS_DIR = Path(__file__).parent / "builtins"
-
 
 class AgentFactory(NamedTuple):
     """Simple container for an agent factory function and its description."""
@@ -127,11 +124,15 @@ def agent_definition_to_factory(
       `AgentContext`.
     - `model: inherit` preserves the parent LLM; an explicit model name
       creates a copy via `model_copy(update=...)`.
+
+    Raises:
+        ValueError: If a tool provided to the agent is not registered.
     """
 
     def _factory(llm: "LLM") -> "Agent":
         from openhands.sdk.agent.agent import Agent
         from openhands.sdk.context.agent_context import AgentContext
+        from openhands.sdk.tool.registry import list_registered_tools
         from openhands.sdk.tool.spec import Tool
 
         # Handle model override
@@ -147,7 +148,15 @@ def _factory(llm: "LLM") -> "Agent":
         )
 
         # Resolve tools
-        tools = [Tool(name=tool_name) for tool_name in agent_def.tools]
+        tools: list[Tool] = []
+        registered_tools: set[str] = set(list_registered_tools())
+        for tool_name in agent_def.tools:
+            if tool_name not in registered_tools:
+                raise ValueError(
+                    f"Tool '{tool_name}' not registered"
+                    f"but was given to agent {agent_def.name}."
+                )
+            tools.append(Tool(name=tool_name))
 
         return Agent(
             llm=llm,
@@ -235,35 +244,6 @@ def register_plugin_agents(agents: list[AgentDefinition]) -> list[str]:
     return registered
 
 
-def register_builtins_agents() -> list[str]:
-    """Load and register SDK builtin agents from ``subagent/builtins/*.md``.
-
-    They are registered via ``register_agent_if_absent`` and will not
-    overwrite agents already registered by programmatic calls, plugins,
-    or project/user-level file-based definitions.
-
-    Returns:
-        List of agent names that were actually registered.
-    """
-    builtins_agents_def = load_agents_from_dir(BUILTINS_DIR)
-
-    registered: list[str] = []
-    for agent_def in builtins_agents_def:
-        factory = agent_definition_to_factory(agent_def)
-        was_registered = register_agent_if_absent(
-            name=agent_def.name,
-            factory_func=factory,
-            description=agent_def.description or f"Agent: {agent_def.name}",
-        )
-        if was_registered:
-            registered.append(agent_def.name)
-            logger.info(
-                f"Registered file-based agent '{agent_def.name}'"
-                + (f" from {agent_def.source}" if agent_def.source else "")
-            )
-    return registered
-
-
 def get_agent_factory(name: str | None) -> AgentFactory:
     """
     Get a registered agent factory by name.
diff --git a/openhands-tools/openhands/tools/__init__.py b/openhands-tools/openhands/tools/__init__.py
index 4e10a017bf..622b2e954c 100644
--- a/openhands-tools/openhands/tools/__init__.py
+++ b/openhands-tools/openhands/tools/__init__.py
@@ -23,6 +23,7 @@
 from openhands.tools.preset.default import (
     get_default_agent,
     get_default_tools,
+    register_builtins_agents,
     register_default_tools,
 )
 from openhands.tools.task_tracker import TaskTrackerTool
@@ -44,4 +45,5 @@
     "get_default_agent",
     "get_default_tools",
     "register_default_tools",
+    "register_builtins_agents",
 ]
diff --git a/openhands-tools/openhands/tools/preset/__init__.py b/openhands-tools/openhands/tools/preset/__init__.py
index cc44e66ce4..aa07aa4d2e 100644
--- a/openhands-tools/openhands/tools/preset/__init__.py
+++ b/openhands-tools/openhands/tools/preset/__init__.py
@@ -18,7 +18,7 @@
   setups.
 """
 
-from .default import get_default_agent
+from .default import get_default_agent, register_builtins_agents
 from .gemini import get_gemini_agent, get_gemini_tools
 from .gpt5 import get_gpt5_agent
 from .planning import get_planning_agent
@@ -30,4 +30,5 @@
     "get_gemini_tools",
     "get_gpt5_agent",
     "get_planning_agent",
+    "register_builtins_agents",
 ]
diff --git a/openhands-tools/openhands/tools/preset/default.py b/openhands-tools/openhands/tools/preset/default.py
index 95ef6535fb..59385215da 100644
--- a/openhands-tools/openhands/tools/preset/default.py
+++ b/openhands-tools/openhands/tools/preset/default.py
@@ -1,12 +1,15 @@
 """Default preset configuration for OpenHands agents."""
 
-from openhands.sdk import Agent
+from pathlib import Path
+
+from openhands.sdk import Agent, agent_definition_to_factory, load_agents_from_dir
 from openhands.sdk.context.condenser import (
     LLMSummarizingCondenser,
 )
 from openhands.sdk.context.condenser.base import CondenserBase
 from openhands.sdk.llm.llm import LLM
 from openhands.sdk.logger import get_logger
+from openhands.sdk.subagent import register_agent_if_absent
 from openhands.sdk.tool import Tool
 
 
@@ -83,3 +86,52 @@ def get_default_agent(
         ),
     )
     return agent
+
+
+def register_builtins_agents(cli_mode: bool = False) -> list[str]:
+    """Load and register builtin agents from ``subagent/*.md``.
+
+    They are registered via `register_agent_if_absent` and will not
+    overwrite agents already registered by programmatic calls, plugins,
+    or project/user-level file-based definitions.
+
+    Args:
+        cli_mode: Whether to load the default agent in cli mode or not.
+
+    Returns:
+        List of agents which were actually registered.
+    """
+    register_default_tools(
+        # Disable browser tools in CLI mode
+        enable_browser=not cli_mode,
+    )
+
+    subagent_dir = Path(__file__).parent / "subagents"
+    builtins_agents_def = load_agents_from_dir(subagent_dir)
+
+    # if we are in cli mode, we filter out the default agent (with browser tool)
+    # otherwise, we filter out the default cli agent
+    if cli_mode:
+        builtins_agents_def = [
+            agent for agent in builtins_agents_def if agent.name != "default"
+        ]
+    else:
+        builtins_agents_def = [
+            agent for agent in builtins_agents_def if agent.name != "default cli mode"
+        ]
+
+    registered: list[str] = []
+    for agent_def in builtins_agents_def:
+        factory = agent_definition_to_factory(agent_def)
+        was_registered = register_agent_if_absent(
+            name=agent_def.name,
+            factory_func=factory,
+            description=agent_def.description or f"Agent: {agent_def.name}",
+        )
+        if was_registered:
+            registered.append(agent_def.name)
+            logger.info(
+                f"Registered file-based agent '{agent_def.name}'"
+                + (f" from {agent_def.source}" if agent_def.source else "")
+            )
+    return registered
diff --git a/openhands-tools/openhands/tools/preset/subagents/bash.md b/openhands-tools/openhands/tools/preset/subagents/bash.md
new file mode 100644
index 0000000000..2e4c10aa2b
--- /dev/null
+++ b/openhands-tools/openhands/tools/preset/subagents/bash.md
@@ -0,0 +1,36 @@
+---
+name: bash
+model: inherit
+description: >-
+  Command execution specialist (terminal only).
+  <example>Run a shell command</example>
+  <example>Execute a build or test script</example>
+  <example>Check system information or process status</example>
+tools:
+  - terminal
+---
+
+You are a command-line execution specialist. Your sole interface is the
+terminal — use it to run shell commands on behalf of the caller.
+
+## Core capabilities
+
+- Execute arbitrary shell commands (bash/sh).
+- Run builds, tests, linters, formatters, and other development tooling.
+- Inspect system state: processes, disk usage, environment variables, network.
+- Perform git operations (commit, push, rebase, etc.).
+
+## Guidelines
+
+1. **Be precise.** Run exactly what was requested. Do not add extra flags or
+   steps unless they are necessary for correctness.
+2. **Check before destroying.** For destructive operations (`rm -rf`, `git
+   reset --hard`, `DROP TABLE`, etc.), confirm the intent and scope before
+   executing.
+3. **Report results clearly.** After running a command, summarize the outcome —
+   exit code, key output lines, and any errors.
+4. **Chain when appropriate.** Use `&&` to chain dependent commands so later
+   steps only run if earlier ones succeed.
+5. **Avoid interactive commands.** Do not run commands that require interactive
+   input (e.g., `vim`, `less`, `git rebase -i`). Use non-interactive
+   alternatives instead.
diff --git a/openhands-sdk/openhands/sdk/subagent/builtins/default.md b/openhands-tools/openhands/tools/preset/subagents/default.md
similarity index 100%
rename from openhands-sdk/openhands/sdk/subagent/builtins/default.md
rename to openhands-tools/openhands/tools/preset/subagents/default.md
diff --git a/openhands-tools/openhands/tools/preset/subagents/default_cli.md b/openhands-tools/openhands/tools/preset/subagents/default_cli.md
new file mode 100644
index 0000000000..65eaca7074
--- /dev/null
+++ b/openhands-tools/openhands/tools/preset/subagents/default_cli.md
@@ -0,0 +1,8 @@
+---
+name: default cli mode
+description: Default general-purpose agent
+tools:
+  - terminal
+  - file_editor
+  - task_tracker
+---
diff --git a/openhands-tools/openhands/tools/preset/subagents/explore.md b/openhands-tools/openhands/tools/preset/subagents/explore.md
new file mode 100644
index 0000000000..401c16f56b
--- /dev/null
+++ b/openhands-tools/openhands/tools/preset/subagents/explore.md
@@ -0,0 +1,43 @@
+---
+name: explore
+model: inherit
+description: >-
+  Fast codebase exploration agent (read-only).
+  <example>Find files matching a pattern</example>
+  <example>Search code for a keyword or symbol</example>
+  <example>Understand how a module or feature is implemented</example>
+tools:
+  - terminal
+---
+
+You are a codebase exploration specialist. You excel at rapidly navigating,
+searching, and understanding codebases. Your role is strictly **read-only** —
+you never create, modify, or delete files.
+
+## Core capabilities
+
+- **File discovery** — find files by name, extension, or glob pattern.
+- **Content search** — locate code, symbols, and text with regex patterns.
+- **Code reading** — read and analyze source files to answer questions.
+
+## Constraints
+
+- Do **not** create, modify, move, copy, or delete any file.
+- Do **not** run commands that change system state (installs, builds, writes).
+- When using the terminal, restrict yourself to read-only commands:
+  `ls`, `find`, `cat`, `head`, `tail`, `wc`, `git status`, `git log`,
+  `git diff`, `git show`, `git blame`, `tree`, `file`, `stat`, `which`,
+  `echo`, `pwd`, `env`, `printenv`, `grep`, `glob`.
+- Never use redirect operators (`>`, `>>`) or pipe to write commands.
+
+## Workflow guidelines
+
+1. Start broad, then narrow down. Use glob patterns to locate candidate files
+   before reading them.
+2. Prefer `grep` for content searches and `glob` for file-name searches.
+3. When exploring an unfamiliar area, check directory structure first (`ls`,
+   `tree`, or glob `**/*`) before diving into individual files.
+4. Spawn parallel tool calls whenever possible — e.g., grep for a symbol in
+   multiple directories at once — to return results quickly.
+5. Provide concise, structured answers. Summarize findings with file paths and
+   line numbers so the caller can act on them immediately.
diff --git a/openhands-tools/pyproject.toml b/openhands-tools/pyproject.toml
index 244af72200..7fe1eaddbc 100644
--- a/openhands-tools/pyproject.toml
+++ b/openhands-tools/pyproject.toml
@@ -38,3 +38,4 @@ namespaces = true
 
 [tool.setuptools.package-data]
 "*" = ["py.typed", "**/*.j2"]
+"openhands.tools.preset.subagents" = ["*.md"]
diff --git a/tests/sdk/subagent/test_subagent_registry.py b/tests/sdk/subagent/test_subagent_registry.py
index ec38c3090f..d4f61b582e 100644
--- a/tests/sdk/subagent/test_subagent_registry.py
+++ b/tests/sdk/subagent/test_subagent_registry.py
@@ -168,7 +168,7 @@ def test_agent_definition_to_factory_basic() -> None:
         name="test-agent",
         description="A test agent",
         model="inherit",
-        tools=["ReadTool", "GlobTool"],
+        tools=[],
         system_prompt="You are a test agent.",
     )
 
@@ -177,10 +177,8 @@ def test_agent_definition_to_factory_basic() -> None:
     agent = factory(llm)
 
     assert isinstance(agent, Agent)
-    # Check tools
-    tool_names = [t.name for t in agent.tools]
-    assert "ReadTool" in tool_names
-    assert "GlobTool" in tool_names
+    # Check tools are empty
+    assert agent.tools == []
     # Check skill (system prompt as always-active skill)
     assert agent.agent_context is not None
     assert agent.agent_context.system_message_suffix == "You are a test agent."
@@ -230,7 +228,6 @@ def test_agent_definition_to_factory_no_system_prompt() -> None:
         name="no-prompt-agent",
         description="No prompt",
         model="inherit",
-        tools=["ReadTool"],
         system_prompt="",
     )
 
@@ -323,9 +320,6 @@ def test_end_to_end_md_to_factory_to_registry(tmp_path: Path) -> None:
         "name: e2e-test-agent\n"
         "description: End-to-end test agent\n"
         "model: inherit\n"
-        "tools:\n"
-        "  - ReadTool\n"
-        "  - GrepTool\n"
         "---\n\n"
         "You are a test agent for end-to-end testing.\n"
         "Focus on correctness and clarity.\n"
@@ -335,7 +329,6 @@ def test_end_to_end_md_to_factory_to_registry(tmp_path: Path) -> None:
     agent_def = AgentDefinition.load(md_file)
     assert agent_def.name == "e2e-test-agent"
     assert agent_def.description == "End-to-end test agent"
-    assert agent_def.tools == ["ReadTool", "GrepTool"]
 
     # Convert to factory
     factory = agent_definition_to_factory(agent_def)
@@ -360,6 +353,3 @@ def test_end_to_end_md_to_factory_to_registry(tmp_path: Path) -> None:
     )
     agent = retrieved.factory_func(test_llm)
     assert isinstance(agent, Agent)
-    tool_names = [t.name for t in agent.tools]
-    assert "ReadTool" in tool_names
-    assert "GrepTool" in tool_names
diff --git a/tests/tools/delegate/test_delegation.py b/tests/tools/delegate/test_delegation.py
index 0dd87bbc5f..033bfa1e5c 100644
--- a/tests/tools/delegate/test_delegation.py
+++ b/tests/tools/delegate/test_delegation.py
@@ -10,12 +10,12 @@
 from openhands.sdk.conversation.conversation_stats import ConversationStats
 from openhands.sdk.conversation.state import ConversationExecutionStatus
 from openhands.sdk.llm import LLM, TextContent
-from openhands.sdk.subagent.registry import register_builtins_agents
 from openhands.tools.delegate import (
     DelegateExecutor,
     DelegateObservation,
 )
 from openhands.tools.delegate.definition import DelegateAction
+from openhands.tools.preset import register_builtins_agents
 
 
 def create_test_executor_and_parent():
diff --git a/tests/tools/task/test_task_manager.py b/tests/tools/task/test_task_manager.py
index 4755b9b98f..571f65dc1a 100644
--- a/tests/tools/task/test_task_manager.py
+++ b/tests/tools/task/test_task_manager.py
@@ -10,8 +10,8 @@
 from openhands.sdk.subagent.registry import (
     _reset_registry_for_tests,
     register_agent,
-    register_builtins_agents,
 )
+from openhands.tools.preset import register_builtins_agents
 from openhands.tools.task.manager import (
     Task,
     TaskManager,
diff --git a/tests/tools/test_builtin_agents.py b/tests/tools/test_builtin_agents.py
new file mode 100644
index 0000000000..57b9338d12
--- /dev/null
+++ b/tests/tools/test_builtin_agents.py
@@ -0,0 +1,85 @@
+"""Tests for built-in subagents definitions."""
+
+from collections.abc import Iterator
+from pathlib import Path
+from typing import Final
+
+import pytest
+from pydantic import SecretStr
+
+import openhands.tools.preset.default as _preset_default
+from openhands.sdk import LLM, Agent
+from openhands.sdk.subagent.load import load_agents_from_dir
+from openhands.sdk.subagent.registry import (
+    _reset_registry_for_tests,
+    get_agent_factory,
+)
+from openhands.tools.preset.default import register_builtins_agents
+
+
+# Resolve once from the installed package — works regardless of cwd.
+SUBAGENTS_DIR: Final[Path] = Path(_preset_default.__file__).parent / "subagents"
+
+
+@pytest.fixture(autouse=True)
+def _clean_registry() -> Iterator[None]:
+    """Reset the agent registry before and after every test."""
+    _reset_registry_for_tests()
+    yield
+    _reset_registry_for_tests()
+
+
+def _make_test_llm() -> LLM:
+    return LLM(model="gpt-4o", api_key=SecretStr("test-key"), usage_id="test-llm")
+
+
+def test_builtins_contains_expected_agents() -> None:
+    md_files = {f.stem for f in SUBAGENTS_DIR.glob("*.md")}
+    assert {"default", "explore", "bash"}.issubset(md_files)
+
+
+def test_load_all_builtins() -> None:
+    """Every .md file in subagents/ should parse without errors."""
+    agents = load_agents_from_dir(SUBAGENTS_DIR)
+    names = {a.name for a in agents}
+    assert {"default", "explore", "bash"}.issubset(names)
+
+
+@pytest.mark.parametrize(
+    "cli_mode, agent_names",
+    [
+        (False, ["default", "explore", "bash"]),
+        (True, ["default cli mode", "explore", "bash"]),
+    ],
+)
+def test_register_builtins_agents_registers_expected_factories(
+    cli_mode: bool, agent_names: list[str]
+) -> None:
+    register_builtins_agents(cli_mode=cli_mode)
+
+    llm = _make_test_llm()
+    agent_tool_names: dict[str, list[str]] = {}
+    for name in agent_names:
+        factory = get_agent_factory(name)
+        agent = factory.factory_func(llm)
+        assert isinstance(agent, Agent)
+        agent_tool_names[name] = [t.name for t in agent.tools]
+
+    assert len(agent_tool_names) == 3
+
+    if cli_mode:
+        assert agent_tool_names["default cli mode"] == [
+            "terminal",
+            "file_editor",
+            "task_tracker",
+        ]
+    else:
+        assert agent_tool_names["default"] == [
+            "terminal",
+            "file_editor",
+            "task_tracker",
+            "browser_tool_set",
+        ]
+
+    assert agent_tool_names["explore"] == ["terminal"]
+    assert agent_tool_names["bash"] == ["terminal"]