Type alias Chainability

Chainability: {
    ok: true;
    sideEffects: boolean;
} | {
    ok: false;
    code: ChainRefusalCode;
    message: string;
}

The rule's verdict for one step tool: chainable (and whether it has side effects, which decides whether a forge test runs it), or refused with a ChainRefusalCode and a message naming what the host can change.