/** Marker key used to tag a tool result as an agent-handoff directive. @internal */
export declare const AGENT_SWITCH_KEY = "__agent_switch__";
/** Options for {@link agentSwitch}. */
export type AgentSwitchOptions = {
    /** Id of the agent handing off (the current/source agent). Defaults to `''`. */
    from_?: string;
    /** Human-readable reason for the handoff, surfaced in handoff history. Defaults to `''`. */
    reason?: string;
    /**
     * Whether the target agent inherits the current conversation context.
     * Defaults to `true`.
     */
    inheritContext?: boolean;
    /** Extra fields merged into the returned payload. Defaults to `null`. */
    extra?: Record<string, any> | null;
};
/**
 * Build a handoff directive that transfers control to another agent (by id).
 * Return the result from a tool to switch the active agent mid-call; the target
 * must be pre-registered via `AgentOptions.agents`.
 *
 * @param to Id of the agent to switch to.
 */
export declare function agentSwitch(to: string, opts?: AgentSwitchOptions): Record<string, any>;