/**
 * Gemini function-calling schema sanitizer.
 *
 * Normalises an MCP tool's JSON Schema into the subset Gemini's function-calling
 * accepts. `@google/genai`'s processJsonSchema crashes on untyped nodes,
 * `$ref`/`$defs`, and some `anyOf`/`oneOf` shapes, so we rebuild a clean tree:
 * every node gets a concrete `type`, unions collapse to their first concrete
 * branch, and unsupported keywords are dropped.
 *
 * Pure, dependency-free, and assertion-free — values arrive as `unknown` and are
 * narrowed with the `isRecord` guard. Safe to reuse for any Gemini tool path.
 */
/**
 * Rebuild a JSON Schema node into the Gemini-safe subset. Returns a fresh object
 * with a concrete `type` on every node.
 */
export declare function sanitizeSchema(node: unknown): Record<string, unknown>;
/** Tool parameters must be an object schema; force it and sanitize the tree. */
export declare function sanitizeToolParameters(schema: unknown): Record<string, unknown>;
/**
 * Walk a (sanitized) schema and return the first node the google plugin would
 * turn into `undefined` — which genai then crashes on. Returns a human-readable
 * path/reason, or `null` if the schema is safe. After `sanitizeSchema` this
 * should always be `null`; if not, it names the exact offending path.
 */
export declare function findSchemaIssue(node: unknown, pathPrefix?: string): string | null;