diff --git a/src/core/GltfLoader.ts b/src/core/GltfLoader.ts
index acf072f..5516ad9 100644
--- a/src/core/GltfLoader.ts
+++ b/src/core/GltfLoader.ts
@@ -130,12 +130,20 @@ export interface GltfLoaderOptions {
    * @security Never perform additional URI decoding or resolution inside this callback.
    * The loader has already validated and best-effort percent-decoded the URI;
    * re-decoding may re-introduce path-traversal or SSRF vulnerabilities.
-   * If percent-decoding fails due to invalid percent-encoding, the original URI string
-   * (with invalid sequences preserved) may be passed to this callback.
    *
-   * Callback invoked to resolve external buffer URIs referenced by the glTF asset.
-   * Receives a URI string and must return the corresponding binary data.
+   * Optional async callback invoked to resolve external buffer URIs referenced by the
+   * glTF asset (non-`data:` references found in `buffers[].uri`).
    * Required when loading plain `.gltf` files that reference external `.bin` files.
+   *
+   * The callback **must** return a `Promise` that resolves to the raw bytes of the
+   * referenced buffer. Rejections propagate directly from `loadGltf`.
+   *
+   * @param uri The raw URI string extracted from the glTF JSON, already validated
+   *   against the loader's URI whitelist and best-effort percent-decoded. If
+   *   percent-decoding fails due to invalid percent-encoding, the original URI string
+   *   (with invalid sequences preserved) may be passed instead. Do **not** perform
+   *   additional URI resolution or decoding inside this callback.
+   * @returns A `Promise` resolving to the buffer's raw bytes as an `ArrayBuffer`.
    */
   resolveUri?: (uri: string) => Promise<ArrayBuffer>;
   /**
diff --git a/tests/gltf.test.ts b/tests/gltf.test.ts
index 6e4a4a0..bc2acc0 100644
--- a/tests/gltf.test.ts
+++ b/tests/gltf.test.ts
@@ -2365,6 +2365,24 @@ describe('GltfLoaderOptions JSDoc', () => {
     expect(gltfLoaderSource).toContain('percent-decoded');
   });
 
+  it('resolveUri JSDoc explicitly states the callback must return a Promise', () => {
+    expect(gltfLoaderSource).toContain('must** return a `Promise`');
+  });
+
+  it('resolveUri JSDoc documents that rejections propagate from loadGltf', () => {
+    expect(gltfLoaderSource).toContain('Rejections propagate directly from `loadGltf`');
+  });
+
+  it('resolveUri JSDoc has a @param uri tag', () => {
+    const resolveUriJsDoc = extractPrecedingJsDoc(gltfLoaderSource, 'resolveUri?:');
+    expect(resolveUriJsDoc).toContain('@param uri');
+  });
+
+  it('resolveUri JSDoc has a @returns tag', () => {
+    const resolveUriJsDoc = extractPrecedingJsDoc(gltfLoaderSource, 'resolveUri?:');
+    expect(resolveUriJsDoc).toContain('@returns');
+  });
+
   it('resolveUri JSDoc has @security tag at the top of the comment block', () => {
     const resolveUriIndex = gltfLoaderSource.indexOf('resolveUri?:');
     expect(resolveUriIndex).toBeGreaterThan(-1);