trading_agent.backends.claude_tool_allowlist_hook

A PreToolUse hook that lets Claude Code run only trading-agent's own tools.

Claude Code's built-in tools are already switched off with tools=[]. This hook is a second lock: if a later Claude Code version, a plugin or a setting ever offered another tool, the call would still be refused. Claude Code's own Bash in particular would bypass the bwrap sandbox and the risk engine.

Typical usage example:

hook = ClaudeToolAllowlistHook(['mcp__trading_agent__get_time']) hooks = {'PreToolUse': [claude_agent_sdk.HookMatcher(hooks=[hook])]}

ClaudeToolAllowlistHook

ClaudeToolAllowlistHook(allowed_tool_names)

Refuses every tool call whose name is not on the allow list.

Creates the hook.

Parameters:

Name	Type	Description	Default
allowed_tool_names	Sequence[str]	The tool names Claude may call, as Claude Code names them.	required

Source code in src/trading_agent/backends/claude_tool_allowlist_hook.py

def __init__(self, allowed_tool_names: Sequence[str]):
    """Creates the hook.

    Args:
        allowed_tool_names (Sequence[str]): The tool names Claude may call, as Claude Code names them.
    """
    self._allowed_tool_names = set(allowed_tool_names)

__call__ async

__call__(hook_input, tool_use_id, context)

Decides whether one tool call may run.

Parameters:

Name	Type	Description	Default
hook_input	dict[str, Any]	The hook's input from Claude Code, including tool_name.	required
tool_use_id	str | None	The call's identifier, unused.	required
context	Any	The hook context, unused.	required

Returns:

Type	Description
dict[str, Any]	An empty dict to allow the call, or a PreToolUse deny decision.

Source code in src/trading_agent/backends/claude_tool_allowlist_hook.py

async def __call__(
    self,
    hook_input: dict[str, Any],
    tool_use_id: str | None,
    context: Any,
) -> dict[str, Any]:
    """Decides whether one tool call may run.

    Args:
        hook_input (dict[str, Any]): The hook's input from Claude Code, including tool_name.
        tool_use_id (str | None): The call's identifier, unused.
        context (Any): The hook context, unused.

    Returns:
        dict[str, Any]: An empty dict to allow the call, or a PreToolUse deny decision.
    """
    del tool_use_id, context
    tool_name = hook_input.get('tool_name', '')
    if tool_name in self._allowed_tool_names:
        return {}
    return {
        'hookSpecificOutput': {
            'hookEventName': 'PreToolUse',
            'permissionDecision': 'deny',
            'permissionDecisionReason': f"{tool_name} is not one of trading-agent's tools.",
        },
    }