diff --git a/crates/switchyard-translation/src/codecs/anthropic/buffered.rs b/crates/switchyard-translation/src/codecs/anthropic/buffered.rs
index 9282c71ccf..f690b0c650 100644
--- a/crates/switchyard-translation/src/codecs/anthropic/buffered.rs
+++ b/crates/switchyard-translation/src/codecs/anthropic/buffered.rs
@@ -314,10 +314,19 @@ impl FormatCodec for AnthropicMessagesCodec {
         {
             body.insert("thinking".to_string(), thinking.clone());
         }
-        if let Some(effort) = &request.reasoning.effort {
-            body.entry("thinking".to_string())
-                .or_insert_with(|| json!({"type": "adaptive"}));
-            body.insert("output_config".to_string(), json!({"effort": effort}));
+        // OpenAI also accepts "none" and "minimal", which Anthropic rejects as efforts.
+        match request.reasoning.effort.as_deref() {
+            Some("none") => {
+                body.entry("thinking".to_string())
+                    .or_insert_with(|| json!({"type": "disabled"}));
+            }
+            Some(effort) => {
+                let effort = if effort == "minimal" { "low" } else { effort };
+                body.entry("thinking".to_string())
+                    .or_insert_with(|| json!({"type": "adaptive"}));
+                body.insert("output_config".to_string(), json!({"effort": effort}));
+            }
+            None => {}
         }
         if let Some(response_format) = &request.output.response_format
             && let Some(format) = encode_anthropic_output_format(
diff --git a/crates/switchyard-translation/tests/request_translation.rs b/crates/switchyard-translation/tests/request_translation.rs
index 18e1ce4f33..9e72a80291 100644
--- a/crates/switchyard-translation/tests/request_translation.rs
+++ b/crates/switchyard-translation/tests/request_translation.rs
@@ -2879,6 +2879,29 @@ fn openai_request_translates_system_developer_and_reasoning_to_anthropic() -> Te
         output["messages"][0]["content"][0],
         json!({"type": "text", "text": "Describe"})
     );
+
+    // OpenAI also accepts "none" and "minimal", which Anthropic rejects as efforts.
+    for (effort, thinking, anthropic_effort) in [
+        ("none", json!({"type": "disabled"}), None),
+        ("minimal", json!({"type": "adaptive"}), Some(json!("low"))),
+    ] {
+        let mut body = body.clone();
+        body["reasoning_effort"] = json!(effort);
+        let output = engine
+            .translate_request(
+                WireFormat::OpenAiChat,
+                WireFormat::AnthropicMessages,
+                &body,
+                &TranslationPolicy::default(),
+            )?
+            .body;
+        assert_eq!(output["thinking"], thinking, "{effort}");
+        assert_eq!(
+            output["output_config"].get("effort"),
+            anthropic_effort.as_ref(),
+            "{effort}"
+        );
+    }
     Ok(())
 }