diff --git a/open-sse/translator/helpers/claudeHelper.ts b/open-sse/translator/helpers/claudeHelper.ts
index 43b1a73132..6d8c8edb81 100644
--- a/open-sse/translator/helpers/claudeHelper.ts
+++ b/open-sse/translator/helpers/claudeHelper.ts
@@ -302,6 +302,33 @@ export function prepareClaudeRequest(
       }
     }
 
+    // Tools: for non-Anthropic providers (MiniMax and other Anthropic-compatible
+    // Claude-shape endpoints) strip Anthropic-only built-in tools (e.g.
+    // web_search_20250305) and normalize OpenAI-wire-shape tools to the
+    // Anthropic-native shape — fold `function.{name,description,parameters}`
+    // into top-level `{name, description, input_schema}` and drop the stray
+    // `type` field. Without this MiniMax rejects with code 2013 ("invalid
+    // tool type"). Port of upstream decolua/9router@45240c19.
+    if (body.tools && Array.isArray(body.tools) && provider !== "claude") {
+      body.tools = body.tools
+        .filter((tool) => !tool.type || tool.type === "function")
+        .map((tool) => {
+          const t = tool as ClaudeTool & {
+            function?: { name?: string; description?: string; parameters?: unknown };
+            type?: string;
+          };
+          if (t.function) {
+            return {
+              name: t.function.name,
+              description: t.function.description,
+              input_schema: t.function.parameters,
+            } as ClaudeTool;
+          }
+          const { type: _type, ...rest } = t;
+          return rest as ClaudeTool;
+        });
+    }
+
     // Also filter top-level tool declarations with empty names
     if (body.tools && Array.isArray(body.tools)) {
       body.tools = body.tools.filter((tool) => tool.name && tool.name?.trim());
diff --git a/tests/unit/translator-tools-anthropic-shape.test.ts b/tests/unit/translator-tools-anthropic-shape.test.ts
new file mode 100644
index 0000000000..824fe1d1db
--- /dev/null
+++ b/tests/unit/translator-tools-anthropic-shape.test.ts
@@ -0,0 +1,119 @@
+// Port of upstream decolua/9router@45240c19.
+// Anthropic-compatible Claude-shape providers (MiniMax and friends) reject
+// tools that carry a `type` field with error code 2013 ("invalid tool type").
+// When a client sends Anthropic-format requests but the tools are still in
+// OpenAI wire shape — `{ type: "function", function: { name, description,
+// parameters } }` — prepareClaudeRequest() must normalize them to the
+// Anthropic-native shape `{ name, description, input_schema }` before
+// forwarding to non-Anthropic providers. For Anthropic itself ("claude")
+// the shape is left untouched so first-party server-side tools like
+// web_search_20250305 keep flowing.
+import { describe, test } from "node:test";
+import assert from "node:assert/strict";
+import { prepareClaudeRequest } from "../../open-sse/translator/helpers/claudeHelper.ts";
+
+describe("prepareClaudeRequest tool-shape normalization for non-Anthropic providers", () => {
+  const buildBody = () => ({
+    model: "MiniMax-M2.7",
+    messages: [{ role: "user", content: [{ type: "text", text: "hi" }] }],
+    max_tokens: 256,
+    tools: [
+      // OpenAI wire shape inside an Anthropic-format request.
+      {
+        type: "function",
+        function: {
+          name: "get_weather",
+          description: "Get the weather",
+          parameters: {
+            type: "object",
+            properties: { city: { type: "string" } },
+            required: ["city"],
+          },
+        },
+      },
+      // Anthropic-native shape (no `type` field at all) — must pass through unchanged.
+      {
+        name: "lookup_user",
+        description: "Find a user",
+        input_schema: {
+          type: "object",
+          properties: { id: { type: "string" } },
+          required: ["id"],
+        },
+      },
+      // Built-in Anthropic server-side tool that non-Anthropic providers
+      // must NOT receive at all.
+      {
+        type: "web_search_20250305",
+        name: "web_search",
+      },
+    ],
+  });
+
+  test("folds function.{name,description,parameters} and drops `type` for minimax", () => {
+    const body = buildBody();
+    const result = prepareClaudeRequest(body as any, "minimax");
+    assert.ok(Array.isArray(result.tools));
+    // Built-in web_search_20250305 must be stripped for non-Anthropic providers.
+    assert.equal(result.tools!.length, 2);
+
+    const weather = result.tools!.find((t: any) => t.name === "get_weather") as any;
+    assert.ok(weather, "get_weather tool must survive normalization");
+    assert.equal(weather.type, undefined, "`type` must be stripped");
+    assert.equal(weather.function, undefined, "`function` wrapper must be folded");
+    assert.equal(weather.description, "Get the weather");
+    assert.deepEqual(weather.input_schema, {
+      type: "object",
+      properties: { city: { type: "string" } },
+      required: ["city"],
+    });
+
+    const lookup = result.tools!.find((t: any) => t.name === "lookup_user") as any;
+    assert.ok(lookup, "lookup_user tool must survive normalization");
+    assert.equal(lookup.type, undefined, "stray `type` must be stripped");
+    assert.deepEqual(lookup.input_schema, {
+      type: "object",
+      properties: { id: { type: "string" } },
+      required: ["id"],
+    });
+  });
+
+  test("does NOT rewrite tool shape for first-party claude (keeps built-ins)", () => {
+    const body = {
+      model: "claude-sonnet-4-5",
+      messages: [{ role: "user", content: [{ type: "text", text: "hi" }] }],
+      max_tokens: 256,
+      tools: [
+        // Anthropic-native shape.
+        {
+          name: "lookup_user",
+          description: "Find a user",
+          input_schema: {
+            type: "object",
+            properties: { id: { type: "string" } },
+            required: ["id"],
+          },
+        },
+        // Built-in Anthropic server-side tool — MUST be preserved for first-party claude.
+        {
+          type: "web_search_20250305",
+          name: "web_search",
+        },
+      ],
+    };
+    const result = prepareClaudeRequest(body as any, "claude");
+    assert.ok(Array.isArray(result.tools));
+    // Built-in web_search_20250305 must NOT be stripped for Anthropic-native upstream.
+    const webSearch = result.tools!.find((t: any) => t.type === "web_search_20250305");
+    assert.ok(webSearch, "web_search_20250305 must be preserved for claude");
+    assert.equal(webSearch!.type, "web_search_20250305");
+    // Anthropic-shape tool is untouched.
+    const lookup = result.tools!.find((t: any) => t.name === "lookup_user") as any;
+    assert.ok(lookup);
+    assert.deepEqual(lookup.input_schema, {
+      type: "object",
+      properties: { id: { type: "string" } },
+      required: ["id"],
+    });
+  });
+});