ref(agents): Simplify OpenAI provider for gateway compatibility

Remove OpenAI-specific parameters that may cause issues with
OpenAI-compatible gateways (Vercel AI Gateway, Azure OpenAI, etc.):

- Remove reasoningEffort parameter (o1/o3 specific)
- Remove structuredOutputs/strictJsonSchema provider options
- Remove temperature override

The baseURL configuration already supports custom endpoints. Users
just need to set OPENAI_MODEL with the correct format for their
provider (e.g., "openai/gpt-5" for Vercel AI Gateway).

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dcramer

packages/mcp-core/src/internal/agents/anthropic-provider.ts

@@ -20,6 +20,7 @@ export function setAnthropicBaseUrl(baseUrl: string | undefined): void {
  * Retrieve an Anthropic language model configured from environment variables and explicit config.
  *
  * Configuration:
+ * - ANTHROPIC_API_KEY: API key for authentication (required)
  * - ANTHROPIC_MODEL: Model to use (default: "claude-sonnet-4-5") - env var OK
  * - Base URL: Must be set via setAnthropicBaseUrl() - NOT from env vars (security risk)
  */

packages/mcp-core/src/internal/agents/openai-provider.test.ts

@@ -2,62 +2,23 @@ import { describe, it, expect, beforeEach, afterEach } from "vitest";
 import { getOpenAIModel, setOpenAIBaseUrl } from "./openai-provider.js";
 
 describe("openai-provider", () => {
-  const originalEnv = process.env.OPENAI_REASONING_EFFORT;
+  const originalModel = process.env.OPENAI_MODEL;
 
   beforeEach(() => {
     setOpenAIBaseUrl(undefined);
+    // biome-ignore lint/performance/noDelete: Required to properly unset environment variable
+    delete process.env.OPENAI_MODEL;
   });
 
   afterEach(() => {
-    if (originalEnv === undefined) {
+    if (originalModel === undefined) {
       // biome-ignore lint/performance/noDelete: Required to properly unset environment variable
-      delete process.env.OPENAI_REASONING_EFFORT;
+      delete process.env.OPENAI_MODEL;
     } else {
-      process.env.OPENAI_REASONING_EFFORT = originalEnv;
+      process.env.OPENAI_MODEL = originalModel;
     }
   });
 
-  describe("reasoning effort configuration", () => {
-    it("uses default reasoning effort when env var is not set", () => {
-      // biome-ignore lint/performance/noDelete: Required to properly unset environment variable
-      delete process.env.OPENAI_REASONING_EFFORT;
-
-      const model = getOpenAIModel();
-
-      // The model object should be created with default reasoning effort
-      expect(model).toBeDefined();
-      expect(model.modelId).toBe("gpt-5");
-    });
-
-    it("disables reasoning effort when env var is empty string", () => {
-      process.env.OPENAI_REASONING_EFFORT = "";
-
-      const model = getOpenAIModel();
-
-      // The model object should be created without reasoning effort
-      expect(model).toBeDefined();
-      expect(model.modelId).toBe("gpt-5");
-    });
-
-    it("uses specified reasoning effort when env var is set", () => {
-      process.env.OPENAI_REASONING_EFFORT = "high";
-
-      const model = getOpenAIModel();
-
-      // The model object should be created with high reasoning effort
-      expect(model).toBeDefined();
-      expect(model.modelId).toBe("gpt-5");
-    });
-
-    it("throws error for invalid reasoning effort value", () => {
-      process.env.OPENAI_REASONING_EFFORT = "invalid";
-
-      expect(() => getOpenAIModel()).toThrow(
-        'Invalid OPENAI_REASONING_EFFORT value: "invalid". Must be one of: "low", "medium", "high", or "" (empty string to disable). Default is "low".',
-      );
-    });
-  });
-
   describe("base URL configuration", () => {
     it("uses default base URL when not configured", () => {
       const model = getOpenAIModel();
@@ -90,14 +51,11 @@ describe("openai-provider", () => {
     });
 
     it("uses OPENAI_MODEL env var when set", () => {
-      process.env.OPENAI_MODEL = "gpt-4o";
+      process.env.OPENAI_MODEL = "gpt-4-turbo";
 
       const model = getOpenAIModel();
 
-      expect(model.modelId).toBe("gpt-4o");
-
-      // biome-ignore lint/performance/noDelete: Required to properly unset environment variable
-      delete process.env.OPENAI_MODEL;
+      expect(model.modelId).toBe("gpt-4-turbo");
     });
   });
 });

packages/mcp-core/src/internal/agents/openai-provider.ts

@@ -4,11 +4,6 @@ import { USER_AGENT } from "../../version";
 
 // Default configuration constants
 const DEFAULT_OPENAI_MODEL = "gpt-5";
-const VALID_REASONING_EFFORTS = ["low", "medium", "high"] as const;
-const DEFAULT_REASONING_EFFORT: (typeof VALID_REASONING_EFFORTS)[number] =
-  "low";
-
-type ReasoningEffort = (typeof VALID_REASONING_EFFORTS)[number];
 
 // Module-level state for baseURL (set only via explicit configuration, not env vars)
 let configuredBaseUrl: string | undefined;
@@ -24,45 +19,29 @@ export function setOpenAIBaseUrl(baseUrl: string | undefined): void {
 /**
  * Retrieve an OpenAI language model configured from environment variables and explicit config.
  *
+ * Works with:
+ * - OpenAI API directly (default)
+ * - Any OpenAI-compatible API via custom base URL (Vercel AI Gateway, Azure OpenAI, etc.)
+ *
  * Configuration:
+ * - OPENAI_API_KEY: API key for authentication (required)
  * - OPENAI_MODEL: Model to use (default: "gpt-5") - env var OK
- * - OPENAI_REASONING_EFFORT: Reasoning effort for o1 models: "low", "medium", "high", or "" to disable (default: "low") - env var OK
  * - Base URL: Must be set via setOpenAIBaseUrl() - NOT from env vars (security risk)
+ *
+ * Note: Model name format depends on your provider:
+ * - Direct OpenAI: "gpt-4o", "gpt-4-turbo", etc.
+ * - Vercel AI Gateway: "openai/gpt-4o", "anthropic/claude-sonnet-4.5", etc.
+ * - Other providers: Check their documentation
  */
 export function getOpenAIModel(model?: string): LanguageModelV1 {
   const defaultModel = process.env.OPENAI_MODEL || DEFAULT_OPENAI_MODEL;
 
-  // Handle reasoning effort: empty string explicitly disables it, undefined uses default
-  const envReasoningEffort = process.env.OPENAI_REASONING_EFFORT;
-  let reasoningEffort: ReasoningEffort | undefined;
-
-  if (envReasoningEffort === "") {
-    // Empty string explicitly disables reasoning effort
-    reasoningEffort = undefined;
-  } else if (envReasoningEffort === undefined) {
-    // Not set - use default
-    reasoningEffort = DEFAULT_REASONING_EFFORT;
-  } else if (
-    VALID_REASONING_EFFORTS.includes(envReasoningEffort as ReasoningEffort)
-  ) {
-    // Valid value
-    reasoningEffort = envReasoningEffort as ReasoningEffort;
-  } else {
-    // Invalid value - provide helpful error with all valid options
-    const validValues = VALID_REASONING_EFFORTS.map((v) => `"${v}"`).join(", ");
-    throw new Error(
-      `Invalid OPENAI_REASONING_EFFORT value: "${envReasoningEffort}". Must be one of: ${validValues}, or "" (empty string to disable). Default is "${DEFAULT_REASONING_EFFORT}".`,
-    );
-  }
-
   const factory = createOpenAI({
     ...(configuredBaseUrl && { baseURL: configuredBaseUrl }),
     headers: {
       "User-Agent": USER_AGENT,
     },
   });
 
-  return factory(model ?? defaultModel, {
-    ...(reasoningEffort && { reasoningEffort }),
-  });
+  return factory(model ?? defaultModel);
 }

packages/mcp-core/src/internal/agents/provider-factory.ts

@@ -77,8 +77,8 @@ function buildProvider(type: AgentProviderType): EmbeddedAgentProvider {
             strictJsonSchema: false,
           },
         }),
-        // GPT-5 only supports temperature of 1
-        getTemperature: () => 1,
+        // Use default temperature (removed GPT-5 specific override)
+        getTemperature: () => undefined,
       };
   }
 }