diff --git a/src/tools/args.ts b/src/tools/args.ts
index 11b5b8b8..a8daf8fa 100644
--- a/src/tools/args.ts
+++ b/src/tools/args.ts
@@ -84,3 +84,13 @@ function toEJSON<T extends object | undefined>(value: T): T {
 export function zEJSON(): z.AnyZodObject {
     return z.object({}).passthrough().transform(toEJSON) as unknown as z.AnyZodObject;
 }
+
+/**
+ * Serializes data to EJSON format with proper Int64 preservation.
+ * This function ensures that Int64 values are not truncated to JavaScript numbers.
+ * @param value The data to serialize
+ * @returns EJSON string with preserved Int64 precision
+ */
+export function serializeWithInt64Preservation(value: unknown): string {
+    return EJSON.stringify(value, undefined, undefined, { relaxed: false });
+}
diff --git a/src/tools/mongodb/delete/deleteMany.ts b/src/tools/mongodb/delete/deleteMany.ts
index 835cbb4a..a7385019 100644
--- a/src/tools/mongodb/delete/deleteMany.ts
+++ b/src/tools/mongodb/delete/deleteMany.ts
@@ -58,7 +58,7 @@ export class DeleteManyTool extends MongoDBToolBase {
     protected getConfirmationMessage({ database, collection, filter }: ToolArgs<typeof this.argsShape>): string {
         const filterDescription =
             filter && Object.keys(filter).length > 0
-                ? "```json\n" + `{ "filter": ${EJSON.stringify(filter)} }\n` + "```\n\n"
+                ? "```json\n" + `{ "filter": ${EJSON.stringify(filter, undefined, undefined, { relaxed: false })} }\n` + "```\n\n"
                 : "- **All documents** (No filter)\n\n";
         return (
             `You are about to delete documents from the \`${collection}\` collection in the \`${database}\` database:\n\n` +
diff --git a/src/tools/mongodb/metadata/dbStats.ts b/src/tools/mongodb/metadata/dbStats.ts
index 830df410..5b34283e 100644
--- a/src/tools/mongodb/metadata/dbStats.ts
+++ b/src/tools/mongodb/metadata/dbStats.ts
@@ -21,7 +21,7 @@ export class DbStatsTool extends MongoDBToolBase {
         });
 
         return {
-            content: formatUntrustedData(`Statistics for database ${database}`, EJSON.stringify(result)),
+            content: formatUntrustedData(`Statistics for database ${database}`, EJSON.stringify(result, undefined, undefined, { relaxed: false })),
         };
     }
 }
diff --git a/src/tools/mongodb/read/aggregate.ts b/src/tools/mongodb/read/aggregate.ts
index c7bd439a..1be44993 100644
--- a/src/tools/mongodb/read/aggregate.ts
+++ b/src/tools/mongodb/read/aggregate.ts
@@ -138,7 +138,7 @@ export class AggregateTool extends MongoDBToolBase {
                             cursorResults.cappedBy,
                         ].filter((limit): limit is keyof typeof CURSOR_LIMITS_TO_LLM_TEXT => !!limit),
                     }),
-                    ...(cursorResults.documents.length > 0 ? [EJSON.stringify(cursorResults.documents)] : [])
+                    ...(cursorResults.documents.length > 0 ? [EJSON.stringify(cursorResults.documents, undefined, undefined, { relaxed: false })] : [])
                 ),
             };
         } finally {
diff --git a/src/tools/mongodb/read/find.ts b/src/tools/mongodb/read/find.ts
index eb006f33..b4a543bc 100644
--- a/src/tools/mongodb/read/find.ts
+++ b/src/tools/mongodb/read/find.ts
@@ -98,7 +98,7 @@ export class FindTool extends MongoDBToolBase {
                         documents: cursorResults.documents,
                         appliedLimits: [limitOnFindCursor.cappedBy, cursorResults.cappedBy].filter((limit) => !!limit),
                     }),
-                    ...(cursorResults.documents.length > 0 ? [EJSON.stringify(cursorResults.documents)] : [])
+                    ...(cursorResults.documents.length > 0 ? [EJSON.stringify(cursorResults.documents, undefined, undefined, { relaxed: false })] : [])
                 ),
             };
         } finally {