From a95108acac7f25fc5e1c0dcdf16bcc638dca5c00 Mon Sep 17 00:00:00 2001
From: Maxwell Brown <maxwellbrown1990@gmail.com>
Date: Mon, 3 Mar 2025 15:08:38 -0500
Subject: [PATCH] Avoid inclusion of `_tag` in tool call parameters (#4545)

---
 .changeset/wicked-starfishes-bow.md | 5 +++++
 packages/ai/ai/src/Completions.ts   | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/wicked-starfishes-bow.md

diff --git a/.changeset/wicked-starfishes-bow.md b/.changeset/wicked-starfishes-bow.md
new file mode 100644
index 00000000000..4afd4e9156d
--- /dev/null
+++ b/.changeset/wicked-starfishes-bow.md
@@ -0,0 +1,5 @@
+---
+"@effect/ai": patch
+---
+
+Avoid inclusion of `_tag` in tool call JSONSchema
diff --git a/packages/ai/ai/src/Completions.ts b/packages/ai/ai/src/Completions.ts
index 144e11a8f51..885f5412d0f 100644
--- a/packages/ai/ai/src/Completions.ts
+++ b/packages/ai/ai/src/Completions.ts
@@ -315,7 +315,7 @@ const convertTool = <A, I, R>(
 ) => ({
   name,
   description: getDescription(schema.ast),
-  parameters: makeJsonSchema(schema.ast),
+  parameters: makeJsonSchema(AST.omit(schema.ast, ["_tag"])),
   structured
 })