diff --git a/packages/config-loader/src/sources/EnvConfigSource.ts b/packages/config-loader/src/sources/EnvConfigSource.ts
index ccd7e37e11..3f1900b192 100644
--- a/packages/config-loader/src/sources/EnvConfigSource.ts
+++ b/packages/config-loader/src/sources/EnvConfigSource.ts
@@ -73,6 +73,13 @@ export class EnvConfigSource implements ConfigSource {
     yield { configs };
     return;
   }
+
+  toString() {
+    const keys = Object.keys(this.env).filter(key =>
+      key.startsWith('APP_CONFIG_'),
+    );
+    return `EnvConfigSource{count=${keys.length}}`;
+  }
 }
 
 const ENV_PREFIX = 'APP_CONFIG_';
diff --git a/packages/config-loader/src/sources/FileConfigSource.ts b/packages/config-loader/src/sources/FileConfigSource.ts
index 947cdfabf7..b6d7181e02 100644
--- a/packages/config-loader/src/sources/FileConfigSource.ts
+++ b/packages/config-loader/src/sources/FileConfigSource.ts
@@ -162,6 +162,10 @@ export class FileConfigSource implements ConfigSource {
     }
   }
 
+  toString() {
+    return `FileConfigSource{path="${this.#path}"}`;
+  }
+
   #waitForEvent(
     watcher: FSWatcher,
     signal?: AbortSignal,
diff --git a/packages/config-loader/src/sources/MergedConfigSource.ts b/packages/config-loader/src/sources/MergedConfigSource.ts
index 5747669564..45387269dc 100644
--- a/packages/config-loader/src/sources/MergedConfigSource.ts
+++ b/packages/config-loader/src/sources/MergedConfigSource.ts
@@ -97,6 +97,10 @@ export class MergedConfigSource implements ConfigSource {
       }
     }
   }
+
+  toString() {
+    return `MergedConfigSource{${this.sources.map(String).join(', ')}}`;
+  }
 }
 
 // Helper to wait for the next value of the iterator, while decorating the value
diff --git a/packages/config-loader/src/sources/MutableConfigSource.ts b/packages/config-loader/src/sources/MutableConfigSource.ts
index 41f902e6b7..c3d15bf20a 100644
--- a/packages/config-loader/src/sources/MutableConfigSource.ts
+++ b/packages/config-loader/src/sources/MutableConfigSource.ts
@@ -108,4 +108,8 @@ export class MutableConfigSource implements ConfigSource {
     this.#currentData = undefined;
     this.#abortController.abort();
   }
+
+  toString() {
+    return `MutableConfigSource{}`;
+  }
 }
diff --git a/packages/config-loader/src/sources/RemoteConfigSource.ts b/packages/config-loader/src/sources/RemoteConfigSource.ts
index 4d2e03cd01..9de0226b8a 100644
--- a/packages/config-loader/src/sources/RemoteConfigSource.ts
+++ b/packages/config-loader/src/sources/RemoteConfigSource.ts
@@ -116,6 +116,10 @@ export class RemoteConfigSource implements ConfigSource {
     }
   }
 
+  toString() {
+    return `RemoteConfigSource{path="${this.#url}"}`;
+  }
+
   async #load(signal?: AbortSignal): Promise<JsonObject> {
     const res = await fetch(this.#url, {
       signal: signal as import('node-fetch').RequestInit['signal'],
diff --git a/packages/config-loader/src/sources/StaticConfigSource.ts b/packages/config-loader/src/sources/StaticConfigSource.ts
index 7f813b228e..68ccc3353a 100644
--- a/packages/config-loader/src/sources/StaticConfigSource.ts
+++ b/packages/config-loader/src/sources/StaticConfigSource.ts
@@ -138,4 +138,8 @@ export class StaticConfigSource implements ConfigSource {
     yield { configs: [{ data: await this.promise, context: this.context }] };
     return;
   }
+
+  toString() {
+    return `StaticConfigSource{}`;
+  }
 }