From 3f6d15f9aaa0cd67ca5e4cd98fd60431619de2b8 Mon Sep 17 00:00:00 2001
From: David Gardner <dagardner@nvidia.com>
Date: Mon, 9 Nov 2026 17:02:27 -0800
Subject: [PATCH 1/2] fix(translation): reject duplicate Chat Completions tool
 names

Signed-off-by: David Gardner <dagardner@nvidia.com>
---
 .../src/codecs/openai_chat/buffered.rs        |  7 ++++++
 tests/test_translation.py                     | 24 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/crates/switchyard-translation/src/codecs/openai_chat/buffered.rs b/crates/switchyard-translation/src/codecs/openai_chat/buffered.rs
index a6af1d8eb..802a0dcf8 100644
--- a/crates/switchyard-translation/src/codecs/openai_chat/buffered.rs
+++ b/crates/switchyard-translation/src/codecs/openai_chat/buffered.rs
@@ -1202,6 +1202,7 @@ fn media_source_text(source: &MediaSource) -> String {
 
 /// Encodes normalized tool definitions into OpenAI tool JSON.
 pub(crate) fn encode_openai_tools(tools: &[Tool]) -> Result<Value> {
+    let mut names = std::collections::HashSet::new();
     Ok(Value::Array(
         tools
             .iter()
@@ -1211,6 +1212,12 @@ pub(crate) fn encode_openai_tools(tools: &[Tool]) -> Result<Value> {
                         "MCP and provider tool encoding is not implemented".into(),
                     )
                 })?;
+                if !names.insert(tool.name.as_str()) {
+                    return Err(TranslationError::InvalidValue {
+                        path: "$.tools".to_string(),
+                        message: format!("duplicate tool name: {:?}", tool.name),
+                    });
+                }
                 let mut function = json!({
                     "name": tool.name,
                     "description": tool.description.clone().unwrap_or_default(),
diff --git a/tests/test_translation.py b/tests/test_translation.py
index dd903bf9a..c85e9bc4e 100644
--- a/tests/test_translation.py
+++ b/tests/test_translation.py
@@ -252,6 +252,30 @@ def test_response_ir_restores_request_tool_extensions(method) -> None:
             ValueError,
             id="request",
         ),
+        pytest.param(
+            "translate_request",
+            (
+                "openai_responses",
+                "openai_chat",
+                {
+                    "tools": [
+                        {
+                            "type": "namespace",
+                            "name": "a__b",
+                            "tools": [{"type": "function", "name": "c", "parameters": {}}],
+                        },
+                        {
+                            "type": "namespace",
+                            "name": "a",
+                            "tools": [{"type": "function", "name": "b__c", "parameters": {}}],
+                        },
+                    ],
+                },
+            ),
+            {},
+            TranslationError,
+            id="namespace-tool-name-collision",
+        ),
         pytest.param(
             "encode_response",
             ("openai_chat", {}),

From f8cf28fe15c786dad77ebd1b3126c6216776ddb1 Mon Sep 17 00:00:00 2001
From: David Gardner <dagardner@nvidia.com>
Date: Tue, 10 Nov 2026 08:31:31 -0800
Subject: [PATCH 2/2] fix(translation): reject duplicate Anthropic tool names

Signed-off-by: David Gardner <dagardner@nvidia.com>
---
 .../src/codecs/anthropic/buffered.rs          |  7 ++++++
 tests/test_translation.py                     | 24 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/crates/switchyard-translation/src/codecs/anthropic/buffered.rs b/crates/switchyard-translation/src/codecs/anthropic/buffered.rs
index 5639f1765..695a9e544 100644
--- a/crates/switchyard-translation/src/codecs/anthropic/buffered.rs
+++ b/crates/switchyard-translation/src/codecs/anthropic/buffered.rs
@@ -1263,6 +1263,7 @@ fn ensure_anthropic_tool_input_object(arguments: Value) -> Value {
 
 // Encodes normalized tool definitions into Anthropic tool JSON.
 fn encode_anthropic_tools(tools: &[Tool]) -> Result<Value> {
+    let mut names = std::collections::HashSet::new();
     Ok(Value::Array(
         tools
             .iter()
@@ -1277,6 +1278,12 @@ fn encode_anthropic_tools(tools: &[Tool]) -> Result<Value> {
                         "MCP and provider tool encoding is not implemented".into(),
                     )
                 })?;
+                if !names.insert(tool.name.as_str()) {
+                    return Err(TranslationError::InvalidValue {
+                        path: "$.tools".to_string(),
+                        message: format!("duplicate tool name: {:?}", tool.name),
+                    });
+                }
                 let mut item = json!({
                     "name": tool.name,
                     "description": tool.description.clone().unwrap_or_default(),
diff --git a/tests/test_translation.py b/tests/test_translation.py
index c85e9bc4e..fb1de2cbb 100644
--- a/tests/test_translation.py
+++ b/tests/test_translation.py
@@ -276,6 +276,30 @@ def test_response_ir_restores_request_tool_extensions(method) -> None:
             TranslationError,
             id="namespace-tool-name-collision",
         ),
+        pytest.param(
+            "translate_request",
+            (
+                "openai_responses",
+                "anthropic_messages",
+                {
+                    "tools": [
+                        {
+                            "type": "namespace",
+                            "name": "a__b",
+                            "tools": [{"type": "function", "name": "c", "parameters": {}}],
+                        },
+                        {
+                            "type": "namespace",
+                            "name": "a",
+                            "tools": [{"type": "function", "name": "b__c", "parameters": {}}],
+                        },
+                    ],
+                },
+            ),
+            {},
+            TranslationError,
+            id="namespace-tool-name-collision-anthropic",
+        ),
         pytest.param(
             "encode_response",
             ("openai_chat", {}),