diff --git a/src/api/zodSchemas.ts b/src/api/zodSchemas.ts
index 2de0a8fe..6a80f0c5 100644
--- a/src/api/zodSchemas.ts
+++ b/src/api/zodSchemas.ts
@@ -700,9 +700,9 @@ export const CreateVariationDto = z.object({
     variables: z
         .record(
             z.union([
-                z.string(),
-                z.number(),
                 z.boolean(),
+                z.number(),
+                z.string(),
                 z.array(z.unknown()),
                 z.record(z.unknown()),
             ]),
@@ -748,9 +748,9 @@ export const Variation = z.object({
     variables: z
         .record(
             z.union([
-                z.string(),
-                z.number(),
                 z.boolean(),
+                z.number(),
+                z.string(),
                 z.array(z.unknown()),
                 z.record(z.unknown()),
             ]),
@@ -861,9 +861,9 @@ const UpdateVariationDto = z
         variables: z
             .record(
                 z.union([
-                    z.string(),
-                    z.number(),
                     z.boolean(),
+                    z.number(),
+                    z.string(),
                     z.array(z.unknown()),
                     z.record(z.unknown()),
                 ]),
@@ -960,9 +960,9 @@ export const FeatureVariationDto = z.object({
     variables: z
         .record(
             z.union([
-                z.string(),
-                z.number(),
                 z.boolean(),
+                z.number(),
+                z.string(),
                 z.array(z.unknown()),
                 z.record(z.unknown()),
             ]),
@@ -980,9 +980,9 @@ export const UpdateFeatureVariationDto = z
         name: z.string().min(1).max(100),
         variables: z.record(
             z.union([
-                z.string(),
-                z.number(),
                 z.boolean(),
+                z.number(),
+                z.string(),
                 z.array(z.unknown()),
                 z.record(z.unknown()),
             ]),
diff --git a/src/mcp/types.ts b/src/mcp/types.ts
index bf41008d..9d4e405e 100644
--- a/src/mcp/types.ts
+++ b/src/mcp/types.ts
@@ -17,6 +17,9 @@ import {
 } from '../api/zodSchemas'
 import { UpdateFeatureStatusDto } from '../api/schemas'
 
+const VARIATION_VARIABLES_TYPE_HINT =
+    'Variable values must use native JSON types: true/false for booleans, numbers for numeric values, strings only for string values. e.g. { "boolVar": false, "numVar": 42, "stringVar": "value" }'
+
 // Zod schemas for MCP tool arguments
 export const VariableValidationSchema = z.object({
     schemaType: z
@@ -277,7 +280,7 @@ export const CreateFeatureArgsSchema = CreateFeatureDto.extend({
         'Environment-specific configurations (key-value map of environment keys to config)',
     ),
     variations: CreateFeatureDto.shape.variations.describe(
-        'Array of variations for this feature',
+        `Array of variations for this feature. ${VARIATION_VARIABLES_TYPE_HINT}`,
     ),
     controlVariation: CreateFeatureDto.shape.controlVariation.describe(
         'The key of the variation that is used as the control variation for Metrics',
@@ -308,7 +311,9 @@ export const UpdateFeatureArgsSchema = UpdateFeatureDto.extend({
         .describe('Updated array of variables for this feature'),
     variations: UpdateFeatureDto.shape.variations
         .optional()
-        .describe('Updated array of variations for this feature'),
+        .describe(
+            `Updated array of variations for this feature. ${VARIATION_VARIABLES_TYPE_HINT}`,
+        ),
     settings: UpdateFeatureDto.shape.settings
         .optional()
         .describe('Updated feature-level settings configuration'),
@@ -370,8 +375,7 @@ export const ListVariationsArgsSchema = z.object({
     feature_key: z.string().describe('Feature key to list variations for'),
 })
 
-const variablesDescription =
-    'key-value map of variable keys to their values for this variation. { "variableKey1": "value1", "variableKey2": false }'
+const variablesDescription = `key-value map of variable keys to their values for this variation. ${VARIATION_VARIABLES_TYPE_HINT}`
 
 export const CreateVariationArgsSchema = CreateVariationDto.extend({
     feature_key: z.string().describe('Feature key to create variation for'),