feat: add tools option to ClaudeAgentOptions (#389)

Add support for the `tools` option matching the TypeScript SDK, which
controls the base set of available tools separately from
allowed/disallowed tool filtering.

Supports three modes:
- Array of tool names: `["Read", "Edit", "Bash"]`
- Empty array: `[]` (disables all built-in tools)
- Preset object: `{"type": "preset", "preset": "claude_code"}`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude <[email protected]>

Author: ashwin-ant

examples/tools_option.py

@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+"""Example demonstrating the tools option and verifying tools in system message."""
+
+import anyio
+
+from claude_agent_sdk import (
+    AssistantMessage,
+    ClaudeAgentOptions,
+    ResultMessage,
+    SystemMessage,
+    TextBlock,
+    query,
+)
+
+
+async def tools_array_example():
+    """Example with tools as array of specific tool names."""
+    print("=== Tools Array Example ===")
+    print("Setting tools=['Read', 'Glob', 'Grep']")
+    print()
+
+    options = ClaudeAgentOptions(
+        tools=["Read", "Glob", "Grep"],
+        max_turns=1,
+    )
+
+    async for message in query(
+        prompt="What tools do you have available? Just list them briefly.",
+        options=options,
+    ):
+        if isinstance(message, SystemMessage) and message.subtype == "init":
+            tools = message.data.get("tools", [])
+            print(f"Tools from system message: {tools}")
+            print()
+        elif isinstance(message, AssistantMessage):
+            for block in message.content:
+                if isinstance(block, TextBlock):
+                    print(f"Claude: {block.text}")
+        elif isinstance(message, ResultMessage):
+            if message.total_cost_usd:
+                print(f"\nCost: ${message.total_cost_usd:.4f}")
+    print()
+
+
+async def tools_empty_array_example():
+    """Example with tools as empty array (disables all built-in tools)."""
+    print("=== Tools Empty Array Example ===")
+    print("Setting tools=[] (disables all built-in tools)")
+    print()
+
+    options = ClaudeAgentOptions(
+        tools=[],
+        max_turns=1,
+    )
+
+    async for message in query(
+        prompt="What tools do you have available? Just list them briefly.",
+        options=options,
+    ):
+        if isinstance(message, SystemMessage) and message.subtype == "init":
+            tools = message.data.get("tools", [])
+            print(f"Tools from system message: {tools}")
+            print()
+        elif isinstance(message, AssistantMessage):
+            for block in message.content:
+                if isinstance(block, TextBlock):
+                    print(f"Claude: {block.text}")
+        elif isinstance(message, ResultMessage):
+            if message.total_cost_usd:
+                print(f"\nCost: ${message.total_cost_usd:.4f}")
+    print()
+
+
+async def tools_preset_example():
+    """Example with tools preset (all default Claude Code tools)."""
+    print("=== Tools Preset Example ===")
+    print("Setting tools={'type': 'preset', 'preset': 'claude_code'}")
+    print()
+
+    options = ClaudeAgentOptions(
+        tools={"type": "preset", "preset": "claude_code"},
+        max_turns=1,
+    )
+
+    async for message in query(
+        prompt="What tools do you have available? Just list them briefly.",
+        options=options,
+    ):
+        if isinstance(message, SystemMessage) and message.subtype == "init":
+            tools = message.data.get("tools", [])
+            print(f"Tools from system message ({len(tools)} tools): {tools[:5]}...")
+            print()
+        elif isinstance(message, AssistantMessage):
+            for block in message.content:
+                if isinstance(block, TextBlock):
+                    print(f"Claude: {block.text}")
+        elif isinstance(message, ResultMessage):
+            if message.total_cost_usd:
+                print(f"\nCost: ${message.total_cost_usd:.4f}")
+    print()
+
+
+async def main():
+    """Run all examples."""
+    await tools_array_example()
+    await tools_empty_array_example()
+    await tools_preset_example()
+
+
+if __name__ == "__main__":
+    anyio.run(main)

src/claude_agent_sdk/_internal/transport/subprocess_cli.py

@@ -185,6 +185,18 @@ def _build_command(self) -> list[str]:
                     ["--append-system-prompt", self._options.system_prompt["append"]]
                 )
 
+        # Handle tools option (base set of tools)
+        if self._options.tools is not None:
+            tools = self._options.tools
+            if isinstance(tools, list):
+                if len(tools) == 0:
+                    cmd.extend(["--tools", ""])
+                else:
+                    cmd.extend(["--tools", ",".join(tools)])
+            else:
+                # Preset object - 'claude_code' preset maps to 'default'
+                cmd.extend(["--tools", "default"])
+
         if self._options.allowed_tools:
             cmd.extend(["--allowedTools", ",".join(self._options.allowed_tools)])
 

src/claude_agent_sdk/types.py

@@ -29,6 +29,13 @@ class SystemPromptPreset(TypedDict):
     append: NotRequired[str]
 
 
+class ToolsPreset(TypedDict):
+    """Tools preset configuration."""
+
+    type: Literal["preset"]
+    preset: Literal["claude_code"]
+
+
 @dataclass
 class AgentDefinition:
     """Agent definition configuration."""
@@ -606,6 +613,7 @@ class StreamEvent:
 class ClaudeAgentOptions:
     """Query options for Claude SDK."""
 
+    tools: list[str] | ToolsPreset | None = None
     allowed_tools: list[str] = field(default_factory=list)
     system_prompt: str | SystemPromptPreset | None = None
     mcp_servers: dict[str, McpServerConfig] | str | Path = field(default_factory=dict)

tests/test_transport.py

@@ -647,3 +647,49 @@ def test_sandbox_network_config(self):
         assert network["allowLocalBinding"] is True
         assert network["httpProxyPort"] == 8080
         assert network["socksProxyPort"] == 8081
+
+    def test_build_command_with_tools_array(self):
+        """Test building CLI command with tools as array of tool names."""
+        transport = SubprocessCLITransport(
+            prompt="test",
+            options=make_options(tools=["Read", "Edit", "Bash"]),
+        )
+
+        cmd = transport._build_command()
+        assert "--tools" in cmd
+        tools_idx = cmd.index("--tools")
+        assert cmd[tools_idx + 1] == "Read,Edit,Bash"
+
+    def test_build_command_with_tools_empty_array(self):
+        """Test building CLI command with tools as empty array (disables all tools)."""
+        transport = SubprocessCLITransport(
+            prompt="test",
+            options=make_options(tools=[]),
+        )
+
+        cmd = transport._build_command()
+        assert "--tools" in cmd
+        tools_idx = cmd.index("--tools")
+        assert cmd[tools_idx + 1] == ""
+
+    def test_build_command_with_tools_preset(self):
+        """Test building CLI command with tools preset."""
+        transport = SubprocessCLITransport(
+            prompt="test",
+            options=make_options(tools={"type": "preset", "preset": "claude_code"}),
+        )
+
+        cmd = transport._build_command()
+        assert "--tools" in cmd
+        tools_idx = cmd.index("--tools")
+        assert cmd[tools_idx + 1] == "default"
+
+    def test_build_command_without_tools(self):
+        """Test building CLI command without tools option (default None)."""
+        transport = SubprocessCLITransport(
+            prompt="test",
+            options=make_options(),
+        )
+
+        cmd = transport._build_command()
+        assert "--tools" not in cmd