diff --git a/mcp/src/tools/capi.test.ts b/mcp/src/tools/capi.test.ts
index 68985d8e..7036ff8b 100644
--- a/mcp/src/tools/capi.test.ts
+++ b/mcp/src/tools/capi.test.ts
@@ -36,4 +36,39 @@ describe("buildCapiErrorMessage", () => {
 
     expect(message).not.toContain("可能的 tcb Action");
   });
+
+  it("provides helpful guidance for 400 invalid parameter value errors", () => {
+    const message = buildCapiErrorMessage(
+      "tcb",
+      "CreateEnv",
+      new Error("400 invalid parameter value (abc123/def456)"),
+    );
+
+    expect(message).toContain("参数值无效或不符合 API 要求");
+    expect(message).toContain("逐个检查传入的参数值");
+    expect(message).toContain("参数值类型是否正确");
+    expect(message).toContain("searchKnowledgeBase");
+  });
+
+  it("shows param hints for 400 errors on known tcb actions", () => {
+    const message = buildCapiErrorMessage(
+      "tcb",
+      "DestroyEnv",
+      new Error("400 invalid parameter value"),
+    );
+
+    expect(message).toContain("参数值无效或不符合 API 要求");
+    expect(message).toContain("`EnvId`");
+  });
+
+  it("provides guidance for 400 errors on non-tcb services", () => {
+    const message = buildCapiErrorMessage(
+      "scf",
+      "CreateFunction",
+      new Error("400 invalid parameter value"),
+    );
+
+    expect(message).toContain("参数值无效或不符合 API 要求");
+    expect(message).toContain("逐个检查传入的参数值");
+  });
 });
diff --git a/mcp/src/tools/capi.ts b/mcp/src/tools/capi.ts
index c1f6fca0..08e55a0a 100644
--- a/mcp/src/tools/capi.ts
+++ b/mcp/src/tools/capi.ts
@@ -113,6 +113,8 @@ export function buildCapiErrorMessage(service: AllowedService, action: string, e
     const tcbEntry = service === "tcb" ? findTcbActionEntry(action) : undefined;
     const hasInvalidActionError = /invalid or not found|does not exist|not recognized/i.test(baseMessage);
     const hasParameterError = /parameter\s+`?.+?`?\s+is not recognized|MissingParameter|missing parameter|missing required/i.test(baseMessage);
+    // Detect generic "400 invalid parameter" errors that don't specify which parameter
+    const hasInvalidParameterValueError = /400\s+invalid\s+parameter/i.test(baseMessage);
 
     if (hasInvalidActionError) {
         suggestions.push(
@@ -148,6 +150,33 @@ export function buildCapiErrorMessage(service: AllowedService, action: string, e
         }
     }
 
+    // Handle generic "400 invalid parameter value" errors
+    if (hasInvalidParameterValueError) {
+        suggestions.push("参数值无效或不符合 API 要求。请逐个检查传入的参数值：");
+        suggestions.push("1. 确认参数值类型是否正确（字符串/数字/布尔值/数组/对象）");
+        suggestions.push("2. 确认字符串参数是否符合格式要求（如时间格式、ID格式等）");
+        suggestions.push("3. 确认枚举值是否在允许范围内");
+        suggestions.push("4. 确认必填参数是否已提供且非空");
+        if (service === "tcb" && tcbEntry) {
+            const paramHint = [
+                tcbEntry.paramKeys.length > 0
+                    ? `当前 Action 的参数键：${formatTcbParamKeys(tcbEntry.paramKeys)}`
+                    : "",
+                tcbEntry.requiredKeys.length > 0
+                    ? `必填参数：${formatTcbParamKeys(tcbEntry.requiredKeys)}`
+                    : "",
+            ].filter(Boolean);
+            if (paramHint.length > 0) {
+                suggestions.push(`\`${tcbEntry.action}\` ${paramHint.join("；")}。`);
+            }
+            const paramsTypeHint = formatTcbParamsTypeHint(tcbEntry.action);
+            if (paramsTypeHint) {
+                suggestions.push(paramsTypeHint);
+            }
+        }
+        suggestions.push(`建议使用 searchKnowledgeBase(mode="openapi", query="${action}") 查询该 API 的详细参数说明。`);
+    }
+
     if (/ECONNRESET|socket hang up|ETIMEDOUT|ENOTFOUND/i.test(baseMessage)) {
         suggestions.push("网络请求异常，建议稍后重试，并检查本地网络/代理设置。");
     }