fix(anthropic): add support for Claude thinking API (#671)

Co-authored-by: Claude <[email protected]>

Author: nirga

packages/instrumentation-anthropic/recordings/Test-Anthropic-instrumentation_3769946143/should-set-attributes-in-span-for-beta-messages-with-thinking_2020128547/recording.har

@@ -0,0 +1,223 @@
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packages/instrumentation-anthropic/src/instrumentation.ts

@@ -45,6 +45,7 @@ import type {
   Message,
   MessageStreamEvent,
 } from "@anthropic-ai/sdk/resources/messages";
+import type { MessageCreateParamsNonStreaming as BetaMessageCreateParamsNonStreaming } from "@anthropic-ai/sdk/resources/beta/messages";
 import type { Stream } from "@anthropic-ai/sdk/streaming";
 import type { APIPromise, BaseAnthropic } from "@anthropic-ai/sdk";
 
@@ -72,6 +73,11 @@ export class AnthropicInstrumentation extends InstrumentationBase {
       "create",
       this.patchAnthropic("chat", module),
     );
+    this._wrap(
+      module.Anthropic.Beta.Messages.prototype,
+      "create",
+      this.patchAnthropic("chat", module),
+    );
   }
 
   protected init(): InstrumentationModuleDefinition {
@@ -97,6 +103,11 @@ export class AnthropicInstrumentation extends InstrumentationBase {
       "create",
       this.patchAnthropic("chat", moduleExports),
     );
+    this._wrap(
+      moduleExports.Anthropic.Beta.Messages.prototype,
+      "create",
+      this.patchAnthropic("chat", moduleExports),
+    );
     return moduleExports;
   }
 
@@ -108,6 +119,7 @@ export class AnthropicInstrumentation extends InstrumentationBase {
 
     this._unwrap(moduleExports.Anthropic.Completions.prototype, "create");
     this._unwrap(moduleExports.Anthropic.Messages.prototype, "create");
+    this._unwrap(moduleExports.Anthropic.Beta.Messages.prototype, "create");
   }
 
   private patchAnthropic(
@@ -202,6 +214,14 @@ export class AnthropicInstrumentation extends InstrumentationBase {
       attributes[SpanAttributes.LLM_REQUEST_TOP_P] = params.top_p;
       attributes[SpanAttributes.LLM_TOP_K] = params.top_k;
 
+      // Handle thinking parameters (for beta messages)
+      const betaParams = params as BetaMessageCreateParamsNonStreaming;
+      if (betaParams.thinking && betaParams.thinking.type === "enabled") {
+        attributes["llm.request.thinking.type"] = betaParams.thinking.type;
+        attributes["llm.request.thinking.budget_tokens"] =
+          betaParams.thinking.budget_tokens;
+      }
+
       if (type === "completion") {
         attributes[SpanAttributes.LLM_REQUEST_MAX_TOKENS] =
           params.max_tokens_to_sample;

packages/instrumentation-anthropic/test/instrumentation.test.ts

@@ -328,4 +328,101 @@ describe("Test Anthropic instrumentation", async function () {
       "user",
     );
   }).timeout(30000);
+
+  it("should set attributes in span for beta messages with thinking", async () => {
+    const message = await anthropic.beta.messages.create({
+      max_tokens: 2048,
+      betas: ["interleaved-thinking-2025-05-14"],
+      messages: [
+        {
+          role: "user",
+          content: "What is 2+2? Think through this step by step.",
+        },
+      ],
+      model: "claude-opus-4-1-20250805",
+      thinking: {
+        type: "enabled",
+        budget_tokens: 1024,
+      },
+    });
+
+    const spans = memoryExporter.getFinishedSpans();
+    const chatSpan = spans.find((span) => span.name === "anthropic.chat");
+
+    assert.ok(message);
+    assert.ok(chatSpan);
+    assert.strictEqual(
+      chatSpan.attributes[`${SpanAttributes.LLM_REQUEST_MODEL}`],
+      "claude-opus-4-1-20250805",
+    );
+    assert.strictEqual(
+      chatSpan.attributes[`${SpanAttributes.LLM_RESPONSE_MODEL}`],
+      "claude-opus-4-1-20250805",
+    );
+    assert.strictEqual(
+      chatSpan.attributes[`${SpanAttributes.LLM_REQUEST_MAX_TOKENS}`],
+      2048,
+    );
+
+    // Check if thinking parameters are captured (these will fail initially)
+    assert.strictEqual(
+      chatSpan.attributes["llm.request.thinking.type"],
+      "enabled",
+    );
+    assert.strictEqual(
+      chatSpan.attributes["llm.request.thinking.budget_tokens"],
+      1024,
+    );
+
+    // Check prompts
+    assert.strictEqual(
+      chatSpan.attributes[`${SpanAttributes.LLM_PROMPTS}.0.role`],
+      "user",
+    );
+    assert.strictEqual(
+      chatSpan.attributes[`${SpanAttributes.LLM_PROMPTS}.0.content`],
+      "What is 2+2? Think through this step by step.",
+    );
+
+    // Check that we capture both thinking and regular content blocks
+    const content = JSON.parse(
+      chatSpan.attributes[
+        `${SpanAttributes.LLM_COMPLETIONS}.0.content`
+      ] as string,
+    );
+    assert.ok(Array.isArray(content));
+
+    interface ContentBlock {
+      type: string;
+      thinking?: string;
+      text?: string;
+    }
+
+    const thinkingBlock = content.find(
+      (block: ContentBlock) => block.type === "thinking",
+    );
+    const textBlock = content.find(
+      (block: ContentBlock) => block.type === "text",
+    );
+
+    assert.ok(thinkingBlock, "Should contain a thinking block");
+    assert.ok(
+      thinkingBlock.thinking,
+      "Thinking block should have thinking content",
+    );
+    assert.ok(textBlock, "Should contain a text block");
+    assert.ok(textBlock.text, "Text block should have text content");
+
+    // Verify token usage includes thinking tokens
+    const completionTokens =
+      chatSpan.attributes[`${SpanAttributes.LLM_USAGE_COMPLETION_TOKENS}`];
+    const promptTokens =
+      chatSpan.attributes[`${SpanAttributes.LLM_USAGE_PROMPT_TOKENS}`];
+    const totalTokens =
+      chatSpan.attributes[`${SpanAttributes.LLM_USAGE_TOTAL_TOKENS}`];
+
+    assert.ok(completionTokens && +completionTokens > 0);
+    assert.ok(promptTokens && +promptTokens > 0);
+    assert.equal(+promptTokens + +completionTokens, totalTokens);
+  }).timeout(30000);
 });