feat: add ability to specify enabled preview features (#686)

Author: nirinchev

README.md

@@ -369,6 +369,7 @@ The MongoDB MCP Server can be configured using multiple methods, with the follow
 | `exportCleanupIntervalMs`              | `MDB_MCP_EXPORT_CLEANUP_INTERVAL_MS`                | 120000                                                                      | Time in milliseconds between export cleanup cycles that remove expired export files.                                                                                                                    |
 | `atlasTemporaryDatabaseUserLifetimeMs` | `MDB_MCP_ATLAS_TEMPORARY_DATABASE_USER_LIFETIME_MS` | 14400000                                                                    | Time in milliseconds that temporary database users created when connecting to MongoDB Atlas clusters will remain active before being automatically deleted.                                             |
 | `voyageApiKey`                         | `MDB_VOYAGE_API_KEY`                                | <not set>                                                                   | API key for communicating with Voyage AI. Used for generating embeddings for Vector search.                                                                                                             |
+| `previewFeatures`                      | `MDB_MCP_PREVIEW_FEATURES`                          | `[]`                                                                        | An array of preview features to opt into.                                                                                                                                                               |
 
 #### Logger Options
 
@@ -490,6 +491,19 @@ You can disable telemetry using:
 
 > **💡 Platform Note:** For Windows users, see [Environment Variables](#environment-variables) for platform-specific instructions.
 
+#### Opting into Preview Features
+
+The MongoDB MCP Server may offer functionality that is still in development and may change in future releases. These features are considered "preview features" and are not enabled by default. Generally, these features are well tested, but may not offer the complete functionality we intend to provide in the final release or we'd like to gather feedback before making them generally available. To enable one or more preview features, use the `previewFeatures` configuration option.
+
+- For **environment variable** configuration, use a comma-separated string: `export MDB_MCP_PREVIEW_FEATURES="vectorSearch,feature1,feature2"`.
+- For **command-line argument** configuration, use a space-separated string: `--previewFeatures vectorSearch feature1 feature2`.
+
+List of available preview features:
+
+- `vectorSearch` - Enables tools or functionality related to Vector Search in MongoDB Atlas:
+  - Index management, such as creating, listing, and dropping vector search indexes.
+  - Querying collections using vector search capabilities. This requires a configured embedding model that will be used to generate vector representations of the query data.
+
 ### Atlas API Access
 
 To use the Atlas API tools, you'll need to create a service account in MongoDB Atlas:

src/common/config.ts

@@ -10,6 +10,9 @@ import type { Similarity } from "./search/vectorSearchEmbeddingsManager.js";
 import { z } from "zod";
 const levenshtein = levenshteinModule.default;
 
+const previewFeatures = z.enum(["vectorSearch"]);
+export type PreviewFeature = z.infer<typeof previewFeatures>;
+
 // From: https://github.com/mongodb-js/mongosh/blob/main/packages/cli-repl/src/arg-parser.ts
 export const OPTIONS = {
     number: ["maxDocumentsPerQuery", "maxBytesPerQuery"],
@@ -81,7 +84,7 @@ export const OPTIONS = {
         "tlsFIPSMode",
         "version",
     ],
-    array: ["disabledTools", "loggers", "confirmationRequiredTools"],
+    array: ["disabledTools", "loggers", "confirmationRequiredTools", "previewFeatures"],
     alias: {
         h: "help",
         p: "password",
@@ -119,7 +122,7 @@ export const ALL_CONFIG_KEYS = new Set(
         .concat(Object.keys(OPTIONS.alias))
 );
 
-export function validateConfigKey(key: string): { valid: boolean; suggestion?: string } {
+function validateConfigKey(key: string): { valid: boolean; suggestion?: string } {
     if (ALL_CONFIG_KEYS.has(key)) {
         return { valid: true };
     }
@@ -282,6 +285,7 @@ export const UserConfigSchema = z.object({
         .optional()
         .default("euclidean")
         .describe("Default similarity function for vector search: 'euclidean', 'cosine', or 'dotProduct'."),
+    previewFeatures: z.array(previewFeatures).default([]).describe("An array of preview features that are enabled."),
 });
 
 export type UserConfig = z.infer<typeof UserConfigSchema> & CliOptions;
@@ -318,6 +322,7 @@ export const defaultUserConfig: UserConfig = {
     disableEmbeddingsValidation: false,
     vectorSearchDimensions: 1024,
     vectorSearchSimilarityFunction: "euclidean",
+    previewFeatures: [],
 };
 
 export const config = setupUserConfig({
@@ -554,13 +559,13 @@ export function setupUserConfig({
 }: {
     cli: string[];
     env: Record<string, unknown>;
-    defaults: Partial<UserConfig>;
+    defaults: UserConfig;
 }): UserConfig {
-    const userConfig: UserConfig = {
+    const userConfig = {
         ...defaults,
         ...parseEnvConfig(env),
         ...parseCliConfig(cli),
-    } as UserConfig;
+    } satisfies UserConfig;
 
     userConfig.disabledTools = commaSeparatedToArray(userConfig.disabledTools);
     userConfig.loggers = commaSeparatedToArray(userConfig.loggers);

src/common/search/embeddingsProvider.ts

@@ -72,8 +72,8 @@ class VoyageEmbeddingsProvider implements EmbeddingsProvider<VoyageModels, Voyag
         this.voyage = createVoyage({ apiKey: voyageApiKey, fetch: customFetch });
     }
 
-    static isConfiguredIn({ voyageApiKey }: UserConfig): boolean {
-        return !!voyageApiKey;
+    static isConfiguredIn({ voyageApiKey, previewFeatures }: UserConfig): boolean {
+        return previewFeatures.includes("vectorSearch") && !!voyageApiKey;
     }
 
     async embed<Model extends VoyageModels>(

src/tools/mongodb/create/createIndex.ts

@@ -1,7 +1,7 @@
 import { z } from "zod";
 import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
 import { DbOperationArgs, MongoDBToolBase } from "../mongodbTool.js";
-import { type ToolArgs, type OperationType, FeatureFlags } from "../../tool.js";
+import { type ToolArgs, type OperationType } from "../../tool.js";
 import type { IndexDirection } from "mongodb";
 import { quantizationEnum, similarityEnum } from "../../../common/search/vectorSearchEmbeddingsManager.js";
 
@@ -74,7 +74,7 @@ export class CreateIndexTool extends MongoDBToolBase {
                         type: z.literal("classic"),
                         keys: z.object({}).catchall(z.custom<IndexDirection>()).describe("The index definition"),
                     }),
-                    ...(this.isFeatureFlagEnabled(FeatureFlags.VectorSearch) ? [this.vectorSearchIndexDefinition] : []),
+                    ...(this.isFeatureEnabled("vectorSearch") ? [this.vectorSearchIndexDefinition] : []),
                 ])
             )
             .describe(

src/tools/mongodb/delete/dropIndex.ts

@@ -2,15 +2,15 @@ import z from "zod";
 import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
 import type { NodeDriverServiceProvider } from "@mongosh/service-provider-node-driver";
 import { DbOperationArgs, MongoDBToolBase } from "../mongodbTool.js";
-import { type ToolArgs, type OperationType, formatUntrustedData, FeatureFlags } from "../../tool.js";
+import { type ToolArgs, type OperationType, formatUntrustedData } from "../../tool.js";
 
 export class DropIndexTool extends MongoDBToolBase {
     public name = "drop-index";
     protected description = "Drop an index for the provided database and collection.";
     protected argsShape = {
         ...DbOperationArgs,
         indexName: z.string().nonempty().describe("The name of the index to be dropped."),
-        type: this.isFeatureFlagEnabled(FeatureFlags.VectorSearch)
+        type: this.isFeatureEnabled("vectorSearch")
             ? z
                   .enum(["classic", "search"])
                   .describe(

src/tools/mongodb/metadata/collectionIndexes.ts

@@ -1,7 +1,7 @@
 import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
 import { DbOperationArgs, MongoDBToolBase } from "../mongodbTool.js";
 import type { ToolArgs, OperationType } from "../../tool.js";
-import { FeatureFlags, formatUntrustedData } from "../../tool.js";
+import { formatUntrustedData } from "../../tool.js";
 
 type SearchIndexStatus = {
     name: string;
@@ -31,7 +31,7 @@ export class CollectionIndexesTool extends MongoDBToolBase {
         }));
 
         const searchIndexDefinitions: SearchIndexStatus[] = [];
-        if (this.isFeatureFlagEnabled(FeatureFlags.VectorSearch) && (await this.session.isSearchSupported())) {
+        if (this.isFeatureEnabled("vectorSearch") && (await this.session.isSearchSupported())) {
             const searchIndexes = await provider.getSearchIndexes(database, collection);
             searchIndexDefinitions.push(...this.extractSearchIndexDetails(searchIndexes));
         }

src/tools/tool.ts

@@ -6,7 +6,7 @@ import type { Session } from "../common/session.js";
 import { LogId } from "../common/logger.js";
 import type { Telemetry } from "../telemetry/telemetry.js";
 import { type ToolEvent } from "../telemetry/types.js";
-import type { UserConfig } from "../common/config.js";
+import type { PreviewFeature, UserConfig } from "../common/config.js";
 import type { Server } from "../server.js";
 import type { Elicitation } from "../elicitation.js";
 
@@ -15,10 +15,6 @@ export type ToolCallbackArgs<Args extends ZodRawShape> = Parameters<ToolCallback
 
 export type ToolExecutionContext<Args extends ZodRawShape = ZodRawShape> = Parameters<ToolCallback<Args>>[1];
 
-export const enum FeatureFlags {
-    VectorSearch = "vectorSearch",
-}
-
 /**
  * The type of operation the tool performs. This is used when evaluating if a tool is allowed to run based on
  * the config's `disabledTools` and `readOnly` settings.
@@ -325,14 +321,8 @@ export abstract class ToolBase {
         this.telemetry.emitEvents([event]);
     }
 
-    // TODO: Move this to a separate file
-    protected isFeatureFlagEnabled(flag: FeatureFlags): boolean {
-        switch (flag) {
-            case FeatureFlags.VectorSearch:
-                return this.config.voyageApiKey !== "";
-            default:
-                return false;
-        }
+    protected isFeatureEnabled(feature: PreviewFeature): boolean {
+        return this.config.previewFeatures.includes(feature);
     }
 }
 

tests/accuracy/createIndex.test.ts

@@ -137,7 +137,7 @@ describeAccuracyTests(
         },
     ],
     {
-        userConfig: { voyageApiKey: "valid-key" },
+        userConfig: { previewFeatures: "vectorSearch" },
         clusterConfig: {
             search: true,
         },

tests/accuracy/createIndex.vectorSearchDisabled.test.ts

@@ -52,6 +52,6 @@ describeAccuracyTests(
         },
     ],
     {
-        userConfig: { voyageApiKey: "" },
+        userConfig: { previewFeatures: "" },
     }
 );

tests/accuracy/dropIndex.test.ts

@@ -127,7 +127,7 @@ describeAccuracyTests(
     ],
     {
         userConfig: {
-            voyageApiKey: "voyage-api-key",
+            previewFeatures: "vectorSearch",
         },
         clusterConfig: { search: true },
     }