diff --git a/open-sse/translator/helpers/claudeHelper.js b/open-sse/translator/helpers/claudeHelper.js
index a08b6bc5..762f5b03 100644
--- a/open-sse/translator/helpers/claudeHelper.js
+++ b/open-sse/translator/helpers/claudeHelper.js
@@ -76,6 +76,8 @@ export function fixToolUseOrdering(messages) {
   return merged;
 }
 
+const CLAUDE_FORMAT_PROVIDERS_WITHOUT_OUTPUT_CONFIG = new Set(["minimax", "minimax-cn"]);
+
 // Prepare request for Claude format endpoints
 // - Cleanup cache_control
 // - Filter empty messages
@@ -83,6 +85,12 @@ export function fixToolUseOrdering(messages) {
 // - Fix tool_use/tool_result ordering
 // - Apply cloaking (billing header + fake user ID) for OAuth tokens
 export function prepareClaudeRequest(body, provider = null, apiKey = null, connectionId = null) {
+  // MiniMax exposes a Claude-compatible endpoint but rejects Anthropic's extended
+  // structured output parameter with a generic 400 "invalid params" response.
+  if (CLAUDE_FORMAT_PROVIDERS_WITHOUT_OUTPUT_CONFIG.has(provider)) {
+    delete body.output_config;
+  }
+
   // 1. System: remove all cache_control, add only to last block with ttl 1h
   if (body.system && Array.isArray(body.system)) {
     body.system = body.system.map((block, i) => {
diff --git a/tests/unit/translator-request-normalization.test.js b/tests/unit/translator-request-normalization.test.js
index 0a67a91d..7165c9fa 100644
--- a/tests/unit/translator-request-normalization.test.js
+++ b/tests/unit/translator-request-normalization.test.js
@@ -96,6 +96,74 @@ describe("request normalization", () => {
     expect(userMessage.content).toBe("hello\nworld");
   });
 
+  it("translateRequest strips unsupported Anthropic output_config for MiniMax Claude-compatible endpoints", () => {
+    const body = {
+      model: "MiniMax-M2.7",
+      system: [{ type: "text", text: "You are helpful." }],
+      messages: [
+        {
+          role: "user",
+          content: [{ type: "text", text: "continue" }],
+        },
+      ],
+      max_tokens: 1024,
+      output_config: {
+        effort: "medium",
+        format: {
+          type: "json_schema",
+          schema: {
+            type: "object",
+            properties: { title: { type: "string" } },
+            required: ["title"],
+            additionalProperties: false,
+          },
+        },
+      },
+    };
+
+    const result = translateRequest(
+      FORMATS.CLAUDE,
+      FORMATS.CLAUDE,
+      "MiniMax-M2.7",
+      JSON.parse(JSON.stringify(body)),
+      true,
+      null,
+      "minimax",
+    );
+
+    expect(result.output_config).toBeUndefined();
+    expect(result.messages[0].content[0].text).toBe("continue");
+  });
+
+  it("translateRequest preserves output_config for Anthropic Claude", () => {
+    const body = {
+      model: "claude-sonnet-4.5",
+      system: [{ type: "text", text: "You are helpful." }],
+      messages: [
+        {
+          role: "user",
+          content: [{ type: "text", text: "continue" }],
+        },
+      ],
+      max_tokens: 1024,
+      output_config: {
+        format: { type: "json_schema", schema: { type: "object" } },
+      },
+    };
+
+    const result = translateRequest(
+      FORMATS.CLAUDE,
+      FORMATS.CLAUDE,
+      "claude-sonnet-4.5",
+      JSON.parse(JSON.stringify(body)),
+      true,
+      null,
+      "claude",
+    );
+
+    expect(result.output_config).toEqual(body.output_config);
+  });
+
   it("parseSSELine supports provider raw NDJSON stream lines", () => {
     const raw = JSON.stringify({
       model: "gpt-oss:120b",