diff --git a/BUILD.bazel b/BUILD.bazel
index b830a1c866..3519e7d204 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -11,6 +11,7 @@ platform(
         "@platforms//os:linux",
         "@platforms//cpu:x86_64",
     ],
+    missing_toolchain_error = "No Linux x86_64 toolchain matched. Docker/Eagle image builds should pass --platforms=//:linux_x86_64 and --extra_toolchains=@llvm_toolchain_linux//:cc-toolchain-x86_64-linux when compiling C++ code.",
 )
 
 # Platform for cross-compiling to Linux ARM64
@@ -20,6 +21,7 @@ platform(
         "@platforms//os:linux",
         "@platforms//cpu:aarch64",
     ],
+    missing_toolchain_error = "No Linux ARM64 toolchain matched. Shardok ARM64 builds should pass --platforms=//:linux_arm64 and --extra_toolchains=@llvm_toolchain_linux_arm64//:cc-toolchain-aarch64-linux.",
 )
 
 gazelle(name = "gazelle")