diff --git a/common/chat-auto-parser-generator.cpp b/common/chat-auto-parser-generator.cpp
index aa03aea5a91..11744f4c441 100644
--- a/common/chat-auto-parser-generator.cpp
+++ b/common/chat-auto-parser-generator.cpp
@@ -208,8 +208,21 @@ common_peg_parser analyze_tools::build_tool_parser_json_native(parser_build_cont
         tool_start = format.per_call_start;
     }
 
-    return ctx.reasoning_parser + (force_tools ? p.eps() : p.optional(p.content(p.until(tool_start)))) + tools_parser +
-           p.end();
+    if (force_tools) {
+        return ctx.reasoning_parser + tools_parser + p.end();
+    }
+
+    // For templates like Llama 3.3 where tool_start is "{" (no distinctive marker),
+    // content stops at any brace and tools_parser takes over. If the model output
+    // contains JSON that isn't a valid tool call (e.g. user asked for a JSON schema),
+    // the tools parser fails with nothing to absorb the remaining input.
+    //
+    // Without the fallback: braces in content either silently truncate (partial match)
+    // or crash with HTTP 500 (full parse throws). The content-only branch lets the
+    // parser return the entire output as content when tool parsing fails.
+    auto with_tools = ctx.reasoning_parser + p.optional(p.content(p.until(tool_start))) + tools_parser + p.end();
+    auto content_only = ctx.reasoning_parser + p.content(p.rest()) + p.end();
+    return p.choice({with_tools, content_only});
 }
 
 common_peg_parser analyze_tools::build_tool_parser_tag_json(parser_build_context & ctx) const {
diff --git a/tests/test-chat.cpp b/tests/test-chat.cpp
index faac9e73062..035e2e83062 100644
--- a/tests/test-chat.cpp
+++ b/tests/test-chat.cpp
@@ -2009,6 +2009,18 @@ static void test_template_output_peg_parsers(bool detailed_debug) {
         GGML_ASSERT(got_runtime_error  && "throw path should produce std::runtime_error with parse position");
     }
 
+    // Regression: Llama 3.3 tool_start="{" — model output that looks like a tool
+    // call but isn't must not crash. Repro: Llama-3.2-3B temp=0 tools=[get_weather]
+    //   prompt="Write a hello world C program. Just the code, no explanation."
+    //   model outputs: {"name": "main", "parameters": {"argc": "2", ...}}
+    {
+        auto tst = peg_tester("models/templates/meta-llama-Llama-3.3-70B-Instruct.jinja", false);
+        tst.test("{\"name\": \"main\", \"parameters\": {\"argc\": \"2\"}}")
+            .tools({ special_function_tool })
+            .expect(simple_assist_msg("{\"name\": \"main\", \"parameters\": {\"argc\": \"2\"}}"))
+            .run();
+    }
+
     // Kimi-K2-Thinking tests - custom parser
     // Unique feature: tool call ID embeds function name as functions.<name>:<counter>
     {