diff --git a/README.md b/README.md
index 5efaebc..7861353 100644
--- a/README.md
+++ b/README.md
@@ -161,7 +161,7 @@ rep.save('gsm8k.report.json')
 | `--limit N` / `--limit-per-task N` | 全局前 N / 每子集前 N（多科目 bench 用后者；可组合取交集） |
 | `--subset` `--split` `--source` | 覆盖子集 / split / 数据源（可指本地路径离线跑） |
 | `--concurrency N` | 并发（默认 32；长输出 bench 建议 8-16） |
-| `--auto-concurrency` | 自适应并发门：按端点健康状况自动决定并发（健康且供不应求时 +1 爬坡，请求失败 ×0.7 退避，服务端 `/metrics` 可用时按排队信号调节）；当前值显示在进度条 `gate N`。此时 `--concurrency` 是起点不是上限 |
+| `--concurrency auto` | 自适应并发门：从 2 起步，健康且供不应求时 +1 爬坡，请求失败 ×0.7 退避（服务端 `/metrics` 可用时按排队信号调节）；当前值显示在进度条 `gate N` |
 | `--resume [PATH]` | 断点续跑；默认 `<cache-dir>/ckpt/<bench>.jsonl` |
 | `--env NAME` | agent 环境（`bfcl_mock` 等） |
 | `--perf` | 采集流式 TTFT / ITL / 重试率入报告 |
diff --git a/evalharness/cli.py b/evalharness/cli.py
index d351e29..7081be5 100644
--- a/evalharness/cli.py
+++ b/evalharness/cli.py
@@ -1152,12 +1152,6 @@ def build_parser() -> argparse.ArgumentParser:
     p.add_argument('--provider', default='openai-chat',
                    choices=('openai-chat', 'openai-pool'),
                    help='API protocol/provider (default: openai-chat)')
-    p.add_argument('--auto-concurrency', action='store_true',
-                   help='let the per-endpoint adaptive gate decide concurrency '
-                        '(ramps while healthy, backs off x0.7 on failures, '
-                        'server /metrics when available); current limit shows '
-                        'on the progress bar as "gate N". --concurrency '
-                        'becomes the starting point, not a cap')
     p.add_argument('--judge-model', '--judge', dest='judge', default='',
                    help='judge model name with --judge-api-url, or full spec')
     p.add_argument('--judge-api-url', default='',
@@ -1185,9 +1179,10 @@ def build_parser() -> argparse.ArgumentParser:
                    help='send tools as text instead of native tool calls')
     p.add_argument('--env', default='', help="agent environment (e.g. 'bfcl_mock') -> message pump")
     p.add_argument('--concurrency', default='32',
-                   help="parallel model calls (default 32); 'auto' = same as "
-                        "--auto-concurrency (the adaptive gate decides, this "
-                        "value becomes its starting point)")
+                   help="parallel model calls (default 32); 'auto' = the "
+                        "adaptive gate decides (starts at 2, ramps +1 while "
+                        "healthy, backs off x0.7 on failures -- see 'gate N' "
+                        "on the progress bar)")
     p.add_argument('--progress', action='store_true', default=True,
                    help='show per-sample progress (default: on)')
     p.add_argument('--no-progress', dest='progress', action='store_false',
@@ -1257,7 +1252,7 @@ def main(argv=None) -> int:
     # an int + the flag
     if str(getattr(args, 'concurrency', '32')).strip().lower() == 'auto':
         args.auto_concurrency = True
-        args.concurrency = 8
+        args.concurrency = 2   # gate start; it ramps on its own signals
     else:
         args.concurrency = int(args.concurrency)
     return args.func(args)