diff --git a/include/amduat/format/pel.h b/include/amduat/format/pel.h
index 0880af3..0f27afd 100644
--- a/include/amduat/format/pel.h
+++ b/include/amduat/format/pel.h
@@ -28,6 +28,17 @@ const char *amduat_format_pel_store_error_name(
 const char *amduat_format_pel_kernel_kind_name(
     amduat_pel_kernel_op_kind_t kind);
 
+bool amduat_format_diagnostics_text(
+    FILE *stream,
+    const char *prefix,
+    const amduat_pel_diagnostic_entry_t *diags,
+    size_t diags_len);
+
+bool amduat_format_diagnostics_json(
+    FILE *stream,
+    const amduat_pel_diagnostic_entry_t *diags,
+    size_t diags_len);
+
 bool amduat_format_pel_program(FILE *stream,
                                const amduat_pel_program_t *program,
                                amduat_format_output_t format);
diff --git a/src/near_core/format/pel.c b/src/near_core/format/pel.c
index d71c812..9115b83 100644
--- a/src/near_core/format/pel.c
+++ b/src/near_core/format/pel.c
@@ -108,7 +108,25 @@ static char *amduat_format_hex_encode(amduat_octets_t bytes) {
   return hex;
 }
 
-static bool amduat_format_diagnostics_text(
+static bool amduat_is_printable_ascii(amduat_octets_t bytes) {
+  size_t i;
+
+  if (bytes.len == 0) {
+    return true;
+  }
+  if (bytes.data == NULL) {
+    return false;
+  }
+  for (i = 0; i < bytes.len; ++i) {
+    uint8_t c = bytes.data[i];
+    if (c < 0x20u || c > 0x7eu) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool amduat_format_diagnostics_text(
     FILE *stream,
     const char *prefix,
     const amduat_pel_diagnostic_entry_t *diags,
@@ -130,12 +148,17 @@ static bool amduat_format_diagnostics_text(
     fprintf(stream, "%sdiagnostic[%zu].code=%u\n", prefix, i, diags[i].code);
     fprintf(stream, "%sdiagnostic[%zu].message_hex=%s\n",
             prefix, i, msg_hex);
+    if (amduat_is_printable_ascii(diags[i].message)) {
+      fprintf(stream, "%sdiagnostic[%zu].message=%.*s\n",
+              prefix, i, (int)diags[i].message.len,
+              (const char *)diags[i].message.data);
+    }
     free(msg_hex);
   }
   return true;
 }
 
-static bool amduat_format_diagnostics_json(
+bool amduat_format_diagnostics_json(
     FILE *stream,
     const amduat_pel_diagnostic_entry_t *diags,
     size_t diags_len) {
@@ -156,6 +179,13 @@ static bool amduat_format_diagnostics_json(
       free(msg_hex);
       return false;
     }
+    if (amduat_is_printable_ascii(diags[i].message)) {
+      fputs(",\"message\":", stream);
+      if (!amduat_format_json_escape(stream, diags[i].message)) {
+        free(msg_hex);
+        return false;
+      }
+    }
     fputs("}", stream);
     free(msg_hex);
   }
diff --git a/src/tools/amduat_pel_cli.c b/src/tools/amduat_pel_cli.c
index 58ea478..9832536 100644
--- a/src/tools/amduat_pel_cli.c
+++ b/src/tools/amduat_pel_cli.c
@@ -878,6 +878,15 @@ static int amduat_pel_cli_cmd_exec(int argc,
             (unsigned int)result.summary.kind);
     fprintf(out_stream, "status_code=%u\n",
             (unsigned int)result.summary.status_code);
+    fprintf(out_stream, "diagnostics_len=%zu\n", result.diagnostics_len);
+    if (!amduat_format_diagnostics_text(out_stream,
+                                        "",
+                                        result.diagnostics,
+                                        result.diagnostics_len)) {
+      fprintf(stderr, "error: failed to format diagnostics\n");
+      exit_code = AMDUAT_PEL_CLI_EXIT_CODEC;
+      goto exec_cleanup;
+    }
     fprintf(out_stream, "outputs_len=%zu\n", outputs_len);
     for (i = 0; i < (int)outputs_len; ++i) {
       fprintf(out_stream, "output_path[%d]=%s/output-%d\n",
@@ -899,6 +908,14 @@ static int amduat_pel_cli_cmd_exec(int argc,
                           result.summary.kind))));
     fprintf(out_stream, ",\"error_kind_code\":%u",
             (unsigned int)result.summary.kind);
+    fputs(",\"diagnostics\":", out_stream);
+    if (!amduat_format_diagnostics_json(out_stream,
+                                        result.diagnostics,
+                                        result.diagnostics_len)) {
+      fprintf(stderr, "error: failed to format diagnostics\n");
+      exit_code = AMDUAT_PEL_CLI_EXIT_CODEC;
+      goto exec_cleanup;
+    }
     fputs(",\"output_paths\":[", out_stream);
     for (i = 0; i < (int)outputs_len; ++i) {
       if (i != 0) {