ipython (persistent Python kernel via IpythonKernelProvisioner), bash/shell, edit/file operations, grep, find. Extension runtime (packages/coding-agent/src/core/extensions/extension-runtime.ts) registers additional tools (AgentTool interface in packages/agent/src/types.ts). Tool execution mode: sequential or parallel (ToolExecutionMode). Before/after hooks (beforeToolCall, afterToolCall) allow blocking and result overrides.
Related: Coding agent index, Extensions