diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index a8f9117b1cc..8dc3b4000a8 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -18,6 +18,11 @@ This repository contains the core of Home Assistant, a Python 3 based home autom
 
 - Python 3.14 explicitly allows `except TypeA, TypeB:` without parentheses.
 
+## Testing
+
+When writing or modifying tests, ensure all test function parameters have type annotations.
+Prefer concrete types (for example, `HomeAssistant`, `MockConfigEntry`, etc.) over `Any`.
+
 ## Good practices
 
 Integrations with Platinum or Gold level in the Integration Quality Scale reflect a high standard of code quality and maintainability. When looking for examples of something, these are good places to start. The level is indicated in the manifest.json of the integration.
diff --git a/AGENTS.md b/AGENTS.md
index 038fa8d021f..888d93ec07e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -15,6 +15,11 @@ This repository contains the core of Home Assistant, a Python 3 based home autom
 
 - Python 3.14 explicitly allows `except TypeA, TypeB:` without parentheses.
 
+## Testing
+
+When writing or modifying tests, ensure all test function parameters have type annotations.
+Prefer concrete types (for example, `HomeAssistant`, `MockConfigEntry`, etc.) over `Any`.
+
 ## Good practices
 
 Integrations with Platinum or Gold level in the Integration Quality Scale reflect a high standard of code quality and maintainability. When looking for examples of something, these are good places to start. The level is indicated in the manifest.json of the integration.