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feat(exec): Add --disable-builtin-tools flag for MCP-only mode #5001

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d8437d1
feat(exec): Add --disable-builtin-tools flag for MCP-only mode
provencher Oct 9, 2025
9c929b8
Merge branch 'main' into feat/exec-tool-control-flags
provencher Oct 9, 2025
36c97da
Merge branch 'main' into feat/exec-tool-control-flags
provencher Oct 9, 2025
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5 changes: 5 additions & 0 deletions codex-rs/core/src/codex.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -452,6 +452,7 @@ impl Session {
use_streamable_shell_tool: config.use_experimental_streamable_shell_tool,
include_view_image_tool: config.include_view_image_tool,
experimental_unified_exec_tool: config.use_experimental_unified_exec_tool,
disable_builtin_tools: config.disable_builtin_tools,
}),
user_instructions,
base_instructions,
Expand Down Expand Up @@ -1201,6 +1202,7 @@ async fn submission_loop(
use_streamable_shell_tool: config.use_experimental_streamable_shell_tool,
include_view_image_tool: config.include_view_image_tool,
experimental_unified_exec_tool: config.use_experimental_unified_exec_tool,
disable_builtin_tools: config.disable_builtin_tools,
});

let new_turn_context = TurnContext {
Expand Down Expand Up @@ -1305,6 +1307,7 @@ async fn submission_loop(
include_view_image_tool: config.include_view_image_tool,
experimental_unified_exec_tool: config
.use_experimental_unified_exec_tool,
disable_builtin_tools: config.disable_builtin_tools,
}),
user_instructions: turn_context.user_instructions.clone(),
base_instructions: turn_context.base_instructions.clone(),
Expand Down Expand Up @@ -1544,6 +1547,7 @@ async fn spawn_review_thread(
use_streamable_shell_tool: false,
include_view_image_tool: false,
experimental_unified_exec_tool: config.use_experimental_unified_exec_tool,
disable_builtin_tools: config.disable_builtin_tools,
});

let base_instructions = REVIEW_PROMPT.to_string();
Expand Down Expand Up @@ -2756,6 +2760,7 @@ mod tests {
use_streamable_shell_tool: config.use_experimental_streamable_shell_tool,
include_view_image_tool: config.include_view_image_tool,
experimental_unified_exec_tool: config.use_experimental_unified_exec_tool,
disable_builtin_tools: config.disable_builtin_tools,
});
let turn_context = TurnContext {
client,
Expand Down
11 changes: 11 additions & 0 deletions codex-rs/core/src/config.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -218,6 +218,10 @@ pub struct Config {
/// Include the `view_image` tool that lets the agent attach a local image path to context.
pub include_view_image_tool: bool,

/// When true, disables all built-in tools (shell, read_file, list_dir, grep_files, apply_patch).
/// MCP tools and web search remain available if configured.
pub disable_builtin_tools: bool,

/// The active profile name used to derive this `Config` (if any).
pub active_profile: Option<String>,

Expand Down Expand Up @@ -957,6 +961,7 @@ pub struct ConfigOverrides {
pub include_view_image_tool: Option<bool>,
pub show_raw_agent_reasoning: Option<bool>,
pub tools_web_search_request: Option<bool>,
pub disable_builtin_tools: Option<bool>,
}

impl Config {
Expand Down Expand Up @@ -985,6 +990,7 @@ impl Config {
include_view_image_tool,
show_raw_agent_reasoning,
tools_web_search_request: override_tools_web_search_request,
disable_builtin_tools,
} = overrides;

let active_profile_name = config_profile_key
Expand Down Expand Up @@ -1177,6 +1183,7 @@ impl Config {
.unwrap_or(false),
use_experimental_use_rmcp_client: cfg.experimental_use_rmcp_client.unwrap_or(false),
include_view_image_tool,
disable_builtin_tools: disable_builtin_tools.unwrap_or(false),
active_profile: active_profile_name,
windows_wsl_setup_acknowledged: cfg.windows_wsl_setup_acknowledged.unwrap_or(false),
disable_paste_burst: cfg.disable_paste_burst.unwrap_or(false),
Expand Down Expand Up @@ -2120,6 +2127,7 @@ model_verbosity = "high"
use_experimental_unified_exec_tool: false,
use_experimental_use_rmcp_client: false,
include_view_image_tool: true,
disable_builtin_tools: false,
active_profile: Some("o3".to_string()),
windows_wsl_setup_acknowledged: false,
disable_paste_burst: false,
Expand Down Expand Up @@ -2183,6 +2191,7 @@ model_verbosity = "high"
use_experimental_unified_exec_tool: false,
use_experimental_use_rmcp_client: false,
include_view_image_tool: true,
disable_builtin_tools: false,
active_profile: Some("gpt3".to_string()),
windows_wsl_setup_acknowledged: false,
disable_paste_burst: false,
Expand Down Expand Up @@ -2261,6 +2270,7 @@ model_verbosity = "high"
use_experimental_unified_exec_tool: false,
use_experimental_use_rmcp_client: false,
include_view_image_tool: true,
disable_builtin_tools: false,
active_profile: Some("zdr".to_string()),
windows_wsl_setup_acknowledged: false,
disable_paste_burst: false,
Expand Down Expand Up @@ -2325,6 +2335,7 @@ model_verbosity = "high"
use_experimental_unified_exec_tool: false,
use_experimental_use_rmcp_client: false,
include_view_image_tool: true,
disable_builtin_tools: false,
active_profile: Some("gpt5".to_string()),
windows_wsl_setup_acknowledged: false,
disable_paste_burst: false,
Expand Down
153 changes: 83 additions & 70 deletions codex-rs/core/src/tools/spec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ pub(crate) struct ToolsConfig {
pub include_view_image_tool: bool,
pub experimental_unified_exec_tool: bool,
pub experimental_supported_tools: Vec<String>,
pub disable_builtin_tools: bool,
}

pub(crate) struct ToolsConfigParams<'a> {
Expand All @@ -39,6 +40,7 @@ pub(crate) struct ToolsConfigParams<'a> {
pub(crate) use_streamable_shell_tool: bool,
pub(crate) include_view_image_tool: bool,
pub(crate) experimental_unified_exec_tool: bool,
pub(crate) disable_builtin_tools: bool,
}

impl ToolsConfig {
Expand All @@ -51,6 +53,7 @@ impl ToolsConfig {
use_streamable_shell_tool,
include_view_image_tool,
experimental_unified_exec_tool,
disable_builtin_tools,
} = params;
let shell_type = if *use_streamable_shell_tool {
ConfigShellToolType::Streamable
Expand Down Expand Up @@ -80,6 +83,7 @@ impl ToolsConfig {
include_view_image_tool: *include_view_image_tool,
experimental_unified_exec_tool: *experimental_unified_exec_tool,
experimental_supported_tools: model_family.experimental_supported_tools.clone(),
disable_builtin_tools: *disable_builtin_tools,
}
}
}
Expand Down Expand Up @@ -742,87 +746,90 @@ pub(crate) fn build_specs(
let view_image_handler = Arc::new(ViewImageHandler);
let mcp_handler = Arc::new(McpHandler);

if config.experimental_unified_exec_tool {
builder.push_spec(create_unified_exec_tool());
builder.register_handler("unified_exec", unified_exec_handler);
} else {
match &config.shell_type {
ConfigShellToolType::Default => {
builder.push_spec(create_shell_tool());
}
ConfigShellToolType::Local => {
builder.push_spec(ToolSpec::LocalShell {});
}
ConfigShellToolType::Streamable => {
builder.push_spec(ToolSpec::Function(
create_exec_command_tool_for_responses_api(),
));
builder.push_spec(ToolSpec::Function(
create_write_stdin_tool_for_responses_api(),
));
builder.register_handler(EXEC_COMMAND_TOOL_NAME, exec_stream_handler.clone());
builder.register_handler(WRITE_STDIN_TOOL_NAME, exec_stream_handler);
// Skip built-in tools if the flag is set
if !config.disable_builtin_tools {
if config.experimental_unified_exec_tool {
builder.push_spec(create_unified_exec_tool());
builder.register_handler("unified_exec", unified_exec_handler);
} else {
match &config.shell_type {
ConfigShellToolType::Default => {
builder.push_spec(create_shell_tool());
}
ConfigShellToolType::Local => {
builder.push_spec(ToolSpec::LocalShell {});
}
ConfigShellToolType::Streamable => {
builder.push_spec(ToolSpec::Function(
create_exec_command_tool_for_responses_api(),
));
builder.push_spec(ToolSpec::Function(
create_write_stdin_tool_for_responses_api(),
));
builder.register_handler(EXEC_COMMAND_TOOL_NAME, exec_stream_handler.clone());
builder.register_handler(WRITE_STDIN_TOOL_NAME, exec_stream_handler);
}
}
}
}

// Always register shell aliases so older prompts remain compatible.
builder.register_handler("shell", shell_handler.clone());
builder.register_handler("container.exec", shell_handler.clone());
builder.register_handler("local_shell", shell_handler);
// Always register shell aliases so older prompts remain compatible.
builder.register_handler("shell", shell_handler.clone());
builder.register_handler("container.exec", shell_handler.clone());
builder.register_handler("local_shell", shell_handler);

if config.plan_tool {
builder.push_spec(PLAN_TOOL.clone());
builder.register_handler("update_plan", plan_handler);
}
if config.plan_tool {
builder.push_spec(PLAN_TOOL.clone());
builder.register_handler("update_plan", plan_handler);
}

if let Some(apply_patch_tool_type) = &config.apply_patch_tool_type {
match apply_patch_tool_type {
ApplyPatchToolType::Freeform => {
builder.push_spec(create_apply_patch_freeform_tool());
}
ApplyPatchToolType::Function => {
builder.push_spec(create_apply_patch_json_tool());
if let Some(apply_patch_tool_type) = &config.apply_patch_tool_type {
match apply_patch_tool_type {
ApplyPatchToolType::Freeform => {
builder.push_spec(create_apply_patch_freeform_tool());
}
ApplyPatchToolType::Function => {
builder.push_spec(create_apply_patch_json_tool());
}
}
builder.register_handler("apply_patch", apply_patch_handler);
}
builder.register_handler("apply_patch", apply_patch_handler);
}

if config
.experimental_supported_tools
.contains(&"grep_files".to_string())
{
let grep_files_handler = Arc::new(GrepFilesHandler);
builder.push_spec_with_parallel_support(create_grep_files_tool(), true);
builder.register_handler("grep_files", grep_files_handler);
}
if config
.experimental_supported_tools
.contains(&"grep_files".to_string())
{
let grep_files_handler = Arc::new(GrepFilesHandler);
builder.push_spec_with_parallel_support(create_grep_files_tool(), true);
builder.register_handler("grep_files", grep_files_handler);
}

if config
.experimental_supported_tools
.contains(&"read_file".to_string())
{
let read_file_handler = Arc::new(ReadFileHandler);
builder.push_spec_with_parallel_support(create_read_file_tool(), true);
builder.register_handler("read_file", read_file_handler);
}
if config
.experimental_supported_tools
.contains(&"read_file".to_string())
{
let read_file_handler = Arc::new(ReadFileHandler);
builder.push_spec_with_parallel_support(create_read_file_tool(), true);
builder.register_handler("read_file", read_file_handler);
}

if config
.experimental_supported_tools
.iter()
.any(|tool| tool == "list_dir")
{
let list_dir_handler = Arc::new(ListDirHandler);
builder.push_spec_with_parallel_support(create_list_dir_tool(), true);
builder.register_handler("list_dir", list_dir_handler);
}
if config
.experimental_supported_tools
.iter()
.any(|tool| tool == "list_dir")
{
let list_dir_handler = Arc::new(ListDirHandler);
builder.push_spec_with_parallel_support(create_list_dir_tool(), true);
builder.register_handler("list_dir", list_dir_handler);
}

if config
.experimental_supported_tools
.contains(&"test_sync_tool".to_string())
{
let test_sync_handler = Arc::new(TestSyncHandler);
builder.push_spec_with_parallel_support(create_test_sync_tool(), true);
builder.register_handler("test_sync_tool", test_sync_handler);
if config
.experimental_supported_tools
.contains(&"test_sync_tool".to_string())
{
let test_sync_handler = Arc::new(TestSyncHandler);
builder.push_spec_with_parallel_support(create_test_sync_tool(), true);
builder.register_handler("test_sync_tool", test_sync_handler);
}
}

if config.web_search_request {
Expand Down Expand Up @@ -914,6 +921,7 @@ mod tests {
use_streamable_shell_tool: false,
include_view_image_tool: true,
experimental_unified_exec_tool: true,
disable_builtin_tools: false,
});
let (tools, _) = build_specs(&config, Some(HashMap::new())).build();

Expand All @@ -934,6 +942,7 @@ mod tests {
use_streamable_shell_tool: false,
include_view_image_tool: true,
experimental_unified_exec_tool: true,
disable_builtin_tools: false,
});
let (tools, _) = build_specs(&config, Some(HashMap::new())).build();

Expand All @@ -956,6 +965,7 @@ mod tests {
use_streamable_shell_tool: false,
include_view_image_tool: false,
experimental_unified_exec_tool: true,
disable_builtin_tools: false,
});
let (tools, _) = build_specs(&config, None).build();

Expand All @@ -977,6 +987,7 @@ mod tests {
use_streamable_shell_tool: false,
include_view_image_tool: false,
experimental_unified_exec_tool: false,
disable_builtin_tools: false,
});
let (tools, _) = build_specs(&config, None).build();

Expand Down Expand Up @@ -1009,6 +1020,7 @@ mod tests {
use_streamable_shell_tool: false,
include_view_image_tool: true,
experimental_unified_exec_tool: true,
disable_builtin_tools: false,
});
let (tools, _) = build_specs(
&config,
Expand Down Expand Up @@ -1470,6 +1482,7 @@ mod tests {
use_streamable_shell_tool: false,
include_view_image_tool: true,
experimental_unified_exec_tool: true,
disable_builtin_tools: false,
});
let (tools, _) = build_specs(
&config,
Expand Down
5 changes: 5 additions & 0 deletions codex-rs/exec/src/cli.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,11 @@ pub struct Cli {
#[arg(long = "include-plan-tool", default_value_t = false)]
pub include_plan_tool: bool,

/// Disable all built-in tools (shell, read_file, list_dir, grep_files, apply_patch).
/// MCP tools and web search will still be available if configured.
#[arg(long = "disable-builtin-tools", default_value_t = false)]
pub disable_builtin_tools: bool,

/// Specifies file where the last message from the agent should be written.
#[arg(long = "output-last-message", short = 'o', value_name = "FILE")]
pub last_message_file: Option<PathBuf>,
Expand Down
2 changes: 2 additions & 0 deletions codex-rs/exec/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,7 @@ pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> any
prompt,
output_schema: output_schema_path,
include_plan_tool,
disable_builtin_tools,
config_overrides,
} = cli;

Expand Down Expand Up @@ -181,6 +182,7 @@ pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> any
include_view_image_tool: None,
show_raw_agent_reasoning: oss.then_some(true),
tools_web_search_request: None,
disable_builtin_tools: Some(disable_builtin_tools),
};
// Parse `-c` overrides.
let cli_kv_overrides = match config_overrides.parse_overrides() {
Expand Down