fix(anthropic): count tokens through the federated credential

A federated deployment holds no static key, so the token counter found none, returned
None, and the caller silently fell back to the local tokenizer. A workload identity
deployment could therefore never get Anthropic's authoritative count.

It now mints one when no static key is configured. The minted token is an sk-ant-oat,
which the existing header builder already sends as a Bearer rather than an x-api-key,
so nothing else on that path changes.

litellm/llms/anthropic/count_tokens/token_counter.py

@@ -54,13 +54,19 @@ class AnthropicTokenCounter(BaseTokenCounter):
         deployment = deployment or {}
         litellm_params: Final = deployment.get("litellm_params", {})
 
-        # Get Anthropic API key from deployment config or environment
-        api_key = litellm_params.get("api_key")
-        if not api_key:
-            api_key = os.getenv("ANTHROPIC_API_KEY")
+        from litellm.llms.anthropic.wif import aget_anthropic_wif_token
+
+        static_key: Final = litellm_params.get("api_key") or os.getenv("ANTHROPIC_API_KEY")
+        # A federated deployment holds no static key by design. Without a minted one this returns
+        # None and the caller silently falls back to the local tokenizer, so a workload identity
+        # deployment would never reach Anthropic's authoritative count. The minted token is an
+        # sk-ant-oat, which get_required_headers already sends as a Bearer rather than x-api-key.
+        api_key: Final = static_key or await aget_anthropic_wif_token(
+            litellm_params, litellm_params.get("api_base"), model_to_use
+        )
 
         if not api_key:
-            verbose_logger.warning("No Anthropic API key found for token counting")
+            verbose_logger.warning("No Anthropic credential found for token counting")
             return None
 
         try:

tests/test_litellm/llms/anthropic/test_count_tokens_oauth.py

@@ -10,6 +10,8 @@ Regression test for https://github.com/BerriAI/litellm/issues/22040
 import os
 import sys
 
+import pytest
+
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), "../../../../..")))
 
 from litellm.llms.anthropic.count_tokens.transformation import (
@@ -78,3 +80,53 @@ class TestCountTokensOAuthHeaders:
         beta_value = headers.get("anthropic-beta", "")
         assert "token-counting" in beta_value, f"token-counting beta missing from OAuth headers: {beta_value}"
         assert "oauth-2025-04-20" in beta_value, f"oauth beta missing from OAuth headers: {beta_value}"
+
+
+class TestCountTokensUsesWorkloadIdentity:
+    """A federated deployment holds no static key. Without minting one, count_tokens returns None
+    and the caller silently falls back to the local tokenizer, so the number a federated
+    deployment reports would never come from Anthropic."""
+
+    @pytest.mark.asyncio
+    async def test_a_federated_deployment_mints_and_counts(self, monkeypatch):
+        from litellm.llms.anthropic.count_tokens import token_counter as token_counter_module
+
+        monkeypatch.delenv("ANTHROPIC_API_KEY", raising=False)
+        minted = "sk-ant-oat01-minted-for-count"
+
+        async def fake_mint(_params, _api_base, _model):
+            return minted
+
+        monkeypatch.setattr(token_counter_module, "aget_anthropic_wif_token", fake_mint, raising=False)
+        monkeypatch.setattr("litellm.llms.anthropic.wif.aget_anthropic_wif_token", fake_mint, raising=False)
+
+        seen: dict[str, object] = {}
+
+        async def fake_request(**kwargs):
+            seen.update(kwargs)
+            return {"input_tokens": 42}
+
+        monkeypatch.setattr(
+            token_counter_module.anthropic_count_tokens_handler,
+            "handle_count_tokens_request",
+            fake_request,
+            raising=False,
+        )
+
+        result = await token_counter_module.AnthropicTokenCounter().count_tokens(
+            model_to_use="claude-sonnet-4-5",
+            messages=[{"role": "user", "content": "hi"}],
+            contents=None,
+            deployment={
+                "litellm_params": {
+                    "model": "anthropic/claude-sonnet-4-5",
+                    "anthropic_federation_rule_id": "fdrl_x",
+                    "anthropic_organization_id": "org-x",
+                }
+            },
+            request_model="claude-sonnet-4-5",
+        )
+
+        assert result is not None
+        assert result.total_tokens == 42
+        assert seen["api_key"] == minted