Adding a Feature Flag-Controlled Tool

This guide covers the extra wiring needed to gate a built-in tool behind a server config toggle. Read docs/guides/adding-builtin-tool.md first for the base tool steps.

Steps

1. Map the config field to a feature flag in src/utils/tools/featureFlagMapper.ts (configToFeatureFlags):

   my_config_field: [FeatureFlag.MY_TOOL],

2. Add the tool-to-flag mapping in BUILTIN_TOOL_FEATURE_FLAGS (or MCP_TOOL_FEATURE_FLAGS for MCP tools):

   [ToolName.MY_TOOL]: FeatureFlag.MY_TOOL,

3. Set requiresFeatureFlag in the tool class:

   override requiresFeatureFlag = FeatureFlag.MY_TOOL;

4. Ensure a config command can toggle the underlying config field so server admins can enable/disable the tool.

Quality Gate

bun run check    # TypeScript strict mode
bun run lint     # Biome formatting

Then verify: toggle the config off → tool should not appear in the LLM’s available tools. Toggle on → tool appears and executes.

Related Docs

• docs/guides/adding-builtin-tool.md — base tool creation steps
• docs/pipelines/tool-loop/ — how feature flags are checked before tools are offered to the LLM