[MCP] implement {get,set}_data and {validate,get}_rules for RTDB MCP #8854

antholeole · 2025-07-15T22:28:00Z

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gemini-code-assist

Summary of Changes

Hello @antholeole, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a comprehensive set of new tools within the Multi-Cloud Platform (MCP) specifically designed for interacting with Firebase Realtime Database (RTDB). The changes enable users to programmatically perform common RTDB operations such as reading and writing data, as well as retrieving and validating security rules, thereby enhancing automation and management capabilities for RTDB instances through the MCP.

Highlights

New Realtime Database (RTDB) Tools: Four new tools have been implemented for Realtime Database: get_data, set_data, get_rules, and validate_rules. These tools expand the MCP's capabilities for RTDB management.
Data Management: get_data allows fetching data from a specified RTDB path, while set_data enables writing JSON data to a given path. Both support custom database URLs and emulators.
Security Rules Management: get_rules provides functionality to retrieve the security rules of an RTDB instance, and validate_rules allows for dry-run validation of RTDB security rules without applying them.
Code Refactoring and Integration: The core logic for updating RTDB rules has been refactored into a reusable updateRulesWithClient function. The MCP framework has been extended to include 'database' as a new server feature, integrating these new RTDB tools.

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antholeole · 2025-07-15T22:29:25Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces new MCP tools for Firebase Realtime Database, allowing users to get/set data and get/validate rules. The implementation includes adding the tool definitions, integrating them into the MCP framework, and refactoring some existing RTDB code. My review identified a critical bug in the refactored rtdb.ts file that would break existing functionality. Additionally, all new RTDB tools share a high-severity issue with hardcoded database URLs, limiting them to a single region. I've also pointed out a couple of medium-severity maintainability issues that should be addressed. Resolving these issues is essential for the correctness and stability of these new features.

gemini-code-assist · 2025-07-15T22:30:57Z

src/rtdb.ts

@@ -32,6 +28,20 @@ export async function updateRules(
    "",
  );
  const client = new Client({ urlPrefix: origin });
+
+  return updateRulesWithClient(client, options);


The call to updateRulesWithClient is missing the src argument. The function is being called with (client, options), but its signature is (client, src, options). This will result in the options object being passed as the rules content, which is incorrect and will break the rule update functionality.

Suggested change

return updateRulesWithClient(client, options);

return updateRulesWithClient(client, src, options);

gemini-code-assist · 2025-07-15T22:30:57Z

src/mcp/tools/database/get_data.ts

+    const dbUrl = new url.URL(
+      databaseUrl
+        ? `${databaseUrl}/${path}.json`
+        : `https://${projectId}-default-rtdb.us-central1.firebasedatabase.app/${path}.json`,
+    );


The default database URL is constructed with a hardcoded region us-central1. This will not work for projects with a default Realtime Database instance in other regions.

gemini-code-assist · 2025-07-15T22:30:57Z

src/mcp/tools/database/get_rules.ts

+    const dbUrl =
+      databaseUrl ?? `https://${projectId}-default-rtdb.us-central1.firebasedatabase.app`;


The default database URL is constructed with a hardcoded region us-central1. This will not work for projects with a default Realtime Database instance in other regions.

gemini-code-assist · 2025-07-15T22:30:57Z

src/mcp/tools/database/set_data.ts

+    const dbUrl = new url.URL(
+      databaseUrl
+        ? `${databaseUrl}/${path}.json`
+        : `https://${projectId}-default-rtdb.us-central1.firebasedatabase.app/${path}.json`,
+    );


The default database URL is constructed with a hardcoded region us-central1. This will not work for projects with a default Realtime Database instance in other regions.

gemini-code-assist · 2025-07-15T22:30:57Z

src/mcp/tools/database/validate_rules.ts

+    const dbUrl =
+      databaseUrl ?? `https://${projectId}-default-rtdb.us-central1.firebasedatabase.app`;


The default database URL is constructed with a hardcoded region us-central1. This will not work for projects with a default Realtime Database instance in other regions.

gemini-code-assist · 2025-07-15T22:30:57Z

src/mcp/util.ts

+/*
+ * Wraps a throwing function with a safe conversion to mcpError.
+ */


This comment appears to be a leftover and doesn't describe any following code. It should be removed to avoid confusion.

gemini-code-assist

Code Review

This pull request implements several Realtime Database tools for the MCP server, including getting/setting data and getting/validating rules. The changes are well-structured, but I've found a few issues. There's a critical bug in the refactored updateRules function where arguments are passed incorrectly. I've also identified some minor issues like malformed error messages, a stray comment, and a duplicated file that should be removed. Please see my detailed comments for suggestions.

gemini-code-assist · 2025-07-15T22:32:36Z

src/rtdb.ts

@@ -32,6 +28,20 @@ export async function updateRules(
    "",
  );
  const client = new Client({ urlPrefix: origin });
+
+  return updateRulesWithClient(client, options);


The call to updateRulesWithClient is missing the src argument and is passing options in its place. This will cause the function to fail at runtime.

The signature for updateRulesWithClient is (client: Client, src: unknown, options: { dryRun?: boolean } = {}).

Suggested change

return updateRulesWithClient(client, options);

return updateRulesWithClient(client, src, options);

gemini-code-assist · 2025-07-15T22:32:36Z

src/mcp/tools/database/set_rules.ts

+import { z } from "zod";
+import { Client } from "../../../apiv2";
+import { tool } from "../../tool";
+import { mcpError, toContent } from "../../util";
+import { updateRulesWithClient } from "../../../rtdb";
+import { getErrMsg } from "../../../error";
+
+export const validate_rules = tool(
+  {
+    name: "validate_rules",
+    description: "Validates an RTDB database's rules",
+    inputSchema: z.object({
+      databaseUrl: z
+        .string()
+        .optional()
+        .describe(
+          "connect to the database at url. If omitted, use default database instance <project>-default-rtdb.firebaseio.com. Can point to emulator URL (e.g. localhost:6000/<instance>)",
+        ),
+      rules: z
+        .string()
+        .describe('The rules object, as a string (ex: {".read": false, ".write": false})'),
+    }),
+    annotations: {
+      title: "Validate Realtime Database rules",
+      idempotentHint: true,
+    },
+
+    _meta: {
+      requiresAuth: true,
+      requiresProject: false,
+    },
+  },
+  async ({ databaseUrl, rules }, { projectId, host }) => {
+    const dbUrl =
+      databaseUrl ?? `https://${projectId}-default-rtdb.us-central1.firebasedatabase.app`;
+
+    const client = new Client({ urlPrefix: dbUrl });
+
+    try {
+      await updateRulesWithClient(client, rules, { dryRun: true });
+    } catch (e: unknown) {
+      host.logger.debug(`failed to update rules at url ${dbUrl}`);
+      return mcpError(getErrMsg(e));
+    }
+
+    return toContent("the inputted rules are valid!");
+  },
+);


This file appears to be a duplicate of validate_rules.ts and is not used in src/mcp/tools/database/index.ts. It also contains a slightly incorrect example for the rules parameter. It seems this file was added by mistake and should be removed to avoid confusion and code duplication.

gemini-code-assist · 2025-07-15T22:32:36Z

src/mcp/tools/database/get_data.ts

+  },
+  async ({ path, databaseUrl }, { projectId, host }) => {
+    if (!path.startsWith("/")) {
+      return mcpError(`paths must start with '/' (you passed ''${path}')`);


The error message for an invalid path has unbalanced single quotes. This will result in a confusing message for the user, for example: paths must start with '/' (you passed ''/mypath').

Suggested change

return mcpError(`paths must start with '/' (you passed ''${path}')`);

return mcpError(`paths must start with '/' (you passed '${path}')`);

gemini-code-assist · 2025-07-15T22:32:36Z

src/mcp/tools/database/get_rules.ts

+      return mcpError(`Failed to fetch current rules. Code: ${response.status}`);
+    }
+
+    const rules = await response.response.text();


For consistency with get_data.ts, please use text(response.body) to read the stream from the response.

Suggested change

const rules = await response.response.text();

const rules = await text(response.body);

gemini-code-assist · 2025-07-15T22:32:36Z

src/mcp/tools/database/set_data.ts

+  },
+  async ({ path, databaseUrl, data }, { projectId, host }) => {
+    if (!path.startsWith("/")) {
+      return mcpError(`paths must start with '/' (you passed ''${path}')`);


The error message for an invalid path has unbalanced single quotes. This will result in a confusing message for the user, for example: paths must start with '/' (you passed ''/mypath').

Suggested change

return mcpError(`paths must start with '/' (you passed ''${path}')`);

return mcpError(`paths must start with '/' (you passed '${path}')`);

gemini-code-assist · 2025-07-15T22:32:36Z

src/mcp/util.ts

+/*
+ * Wraps a throwing function with a safe conversion to mcpError.
+ */


This comment appears to be out of place and does not describe the following function. Please remove it to avoid confusion.

github-project-automation bot added this to [Cloud] Extensions + Functions Jul 15, 2025

antholeole assigned nguymichael Jul 15, 2025

gemini-code-assist bot reviewed Jul 15, 2025

View reviewed changes

[MCP] implement {get,set}_data and {validate,get}_rules for RTDB MCP

bff5222

antholeole force-pushed the oleina/rtdbmcp branch from 51c66d1 to bff5222 Compare July 15, 2025 22:28

gemini-code-assist bot reviewed Jul 15, 2025

View reviewed changes

antholeole unassigned nguymichael Jul 15, 2025

antholeole marked this pull request as draft July 15, 2025 22:34

	return updateRulesWithClient(client, options);
	return updateRulesWithClient(client, src, options);

		const dbUrl =
		databaseUrl ?? `https://${projectId}-default-rtdb.us-central1.firebasedatabase.app`;

	return mcpError(`paths must start with '/' (you passed ''${path}')`);
	return mcpError(`paths must start with '/' (you passed '${path}')`);

	const rules = await response.response.text();
	const rules = await text(response.body);

[MCP] implement {get,set}_data and {validate,get}_rules for RTDB MCP #8854

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[MCP] implement {get,set}_data and {validate,get}_rules for RTDB MCP #8854

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antholeole commented Jul 15, 2025

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