feat(mcp): Adds `dataconnect_compile` tool to MCP server. #8979

mbleigh · 2025-08-15T17:26:19Z

This PR does a few things:

Adds a new dataconnect_compile tool that builds FDC schema/connectors and returns any errors.
Adds a new mcpalpha experiment so that we can gate MCP features on a flag to keep things on master.
Adds a new firebase:dataconnect:schema prompt that is only available with mcpalpha enabled.

gemini-code-assist

Summary of Changes

Hello @mbleigh, 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 significant enhancements to the Firebase Data Connect (FDC) functionality within the MCP server. It adds a new dataconnect_compile tool for validating FDC schemas and connectors, and gates new MCP features behind an mcpalpha experiment flag. Additionally, a new firebase:dataconnect:schema prompt is introduced to facilitate schema generation and updates, accessible when the mcpalpha flag is enabled.

Highlights

New dataconnect_compile Tool: A new tool has been added to the MCP server that allows users to compile Firebase Data Connect schemas and connectors, providing immediate feedback on any build errors.
Introduction of mcpalpha Experiment Flag: A new experiment flag, mcpalpha, has been implemented. This flag enables the gating of early-stage MCP features, allowing for controlled rollout and testing without impacting the main master branch.
New firebase:dataconnect:schema Prompt: A dedicated prompt has been added to assist with generating or updating Firebase Data Connect schemas. This prompt is conditionally available when the mcpalpha experiment flag is active.
Refactoring of Data Connect Utilities: Several utility files related to Data Connect (specifically converter.ts and emulator.ts) have been relocated to a new src/mcp/lib/dataconnect directory, improving code organization and maintainability.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in issue comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

gemini-code-assist

Code Review

This pull request introduces a new dataconnect_compile tool, an mcpalpha experiment, and a new firebase:dataconnect:schema prompt. The changes are well-structured and align with the PR's objectives. I've identified a few minor issues, including a duplicated debug log, an incomplete sentence in a prompt, and a typo in an error message, and have provided suggestions for fixes.

src/mcp/tools/dataconnect/compile.ts

src/mcp/index.ts

src/mcp/prompts/dataconnect/schema.ts

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

…ls into mb/mcp/fdc-compile

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

src/experiments.ts

src/mcp/prompts/dataconnect/schema.ts

src/mcp/tools/dataconnect/compile.ts

src/mcp/util/dataconnect/compile.ts

Co-authored-by: Joe Hanley <[email protected]>

…ls into mb/mcp/fdc-compile

fredzqm · 2025-08-18T20:45:19Z

src/mcp/index.ts

@@ -227,6 +227,10 @@ export class FirebaseMcpServer {
  }

  get availablePrompts(): ServerPrompt[] {
+    this.log(


Is this change intended?

src/mcp/tools/dataconnect/compile.ts

fredzqm · 2025-08-18T22:13:43Z

src/mcp/tools/dataconnect/compile.ts

+      "Use this to compile Firebase Data Connect schema, operations, and/or connectors and check for build errors.",
+    inputSchema: z.object({
+      error_filter: z
+        .enum(["all", "schema", "connectors"])


"connectors" optional doesn't make sense.

If schema is invalid, connectors will return no error, which is mis-leading. This should be either "schema" or "all".

I'll just drop this for now, it can just see all the errors at once.

fredzqm · 2025-08-18T22:14:53Z

src/mcp/util/dataconnect/compile.ts

+  return (
+    errors
+      ?.filter((e) => {
+        const isOperationError = ["query", "mutation"].includes(e.path?.[0] as string);


Not all clients follow the query & mutation convention. Only our CLI init template does.

We should probably not support errorFilter for now.

I can find a correct way to do this later.

No, I believe this will always be correct -- the path is like ["query", "users", "someField"] because it's mapping query { users { someField }}. I believe it will always work.

Oh, I see. This is the GQL path error.

I got it mixed up with the file name.

fredzqm · 2025-08-18T22:18:12Z

src/mcp/prompts/dataconnect/schema.ts

+      },
+    ],
+    annotations: {
+      title: "Deploy to Firebase",


"title" looks off.

I am wondering if it makes more sense to rely on the GiF backend more, which is known to have good accuracy.

I have concerns over lack of eval & performance visibility in local MCP prompts. It gets worse if this tool shadows the dataconnect_generate_schema tool.

[not blocking] Feel free to check this in.

I am trying to figure out where that line should be. Maybe it's edit vs create.

Use GiF API to generate the initial schema and new operations.

Use the local prompts to iterate and edit them. Cursor probably has more local context.

Without evaluation, it's really a pain to figure how the experience is.

I don't think our visibility into GiF is all that much better, though I'd like us to come up with an informal eval system utilizing Gemini CLI for the MCP server generally. This is currently flagged off in the "mcpalpha" experiment so I'm not too worried about it one way or the other for now.

fredzqm · 2025-08-18T22:26:47Z

src/mcp/prompts/dataconnect/schema.ts

+
+==== TASK INSTRUCTIONS ====
+
+1. If Data Connect is marked as \`<UNCONFIGURED>\`, first run the \`firebase_init\` tool with \`{dataconnect: {}}\` arguments to initialize it.


NOTE: for myself. We can pass in appIdea here to let GiF generates the schema and connectors for us

fredzqm · 2025-08-18T22:38:21Z

src/mcp/prompts/dataconnect/schema.ts

+      },
+    ],
+    annotations: {
+      title: "Deploy to Firebase",


[not blocking] Feel free to check this in.

I am trying to figure out where that line should be. Maybe it's edit vs create.

Use GiF API to generate the initial schema and new operations.

Use the local prompts to iterate and edit them. Cursor probably has more local context.

Without evaluation, it's really a pain to figure how the experience is.

fredzqm

Thank you Michael!! Love it!!! 🔥 🔥 🔥

fredzqm · 2025-08-28T20:27:26Z

src/dataconnect/loadAll.ts

+import { load, readFirebaseJson } from "./load";
+import type { Config } from "../config";
+
+export function loadAll(projectId: string, config: Config) {


Since your PR, I added loadAll in a different file~

https://github.com/firebase/firebase-tools/blob/2f0b457b299019ada540f0ebd96c64070af19578/src/dataconnect/load.ts#L61C23-L61C30

fredzqm · 2025-08-28T20:33:38Z

src/mcp/util/dataconnect/compile.ts

+  return (
+    errors
+      ?.filter((e) => {
+        const isOperationError = ["query", "mutation"].includes(e.path?.[0] as string);


Oh, I see. This is the GQL path error.

I got it mixed up with the file name.

mbleigh added 2 commits August 15, 2025 10:22

feat(mcp): Adds dataconnect_compile tool to MCP server.

5393734

revert pnpm

d1905c0

mbleigh requested a review from joehan August 15, 2025 17:26

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

gemini-code-assist bot reviewed Aug 15, 2025

View reviewed changes

rename lib -> util bc gitignore

f8639b7

gemini-code-assist bot reviewed Aug 15, 2025

View reviewed changes

src/mcp/tools/dataconnect/compile.ts Outdated Show resolved Hide resolved

src/mcp/index.ts Outdated Show resolved Hide resolved

src/mcp/prompts/dataconnect/schema.ts Outdated Show resolved Hide resolved

mbleigh and others added 4 commits August 15, 2025 10:30

Update src/mcp/tools/dataconnect/compile.ts

9d4189f

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

remove extra logging

fdbd439

Merge branch 'mb/mcp/fdc-compile' of github.com:firebase/firebase-too…

9aa46c5

…ls into mb/mcp/fdc-compile

Update src/mcp/prompts/dataconnect/schema.ts

7d1b504

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

joehan approved these changes Aug 15, 2025

View reviewed changes

github-project-automation bot moved this to Approved [PR] in [Cloud] Extensions + Functions Aug 15, 2025

mbleigh and others added 3 commits August 15, 2025 11:19

Update src/mcp/tools/dataconnect/compile.ts

5ff2dc6

Co-authored-by: Joe Hanley <[email protected]>

pr feedback

ce98e24

Update src/mcp/tools/dataconnect/compile.ts

b7775df

Co-authored-by: Joe Hanley <[email protected]>

mbleigh enabled auto-merge (squash) August 15, 2025 18:22

Merge branch 'mb/mcp/fdc-compile' of github.com:firebase/firebase-too…

edda60f

…ls into mb/mcp/fdc-compile

fredzqm requested changes Aug 18, 2025

View reviewed changes

github-project-automation bot moved this from Approved [PR] to Changes Requested [PR] in [Cloud] Extensions + Functions Aug 18, 2025

fredzqm reviewed Aug 18, 2025

View reviewed changes

mbleigh added 2 commits August 25, 2025 17:48

merge

f5827a7

Merge branch 'master' into mb/mcp/fdc-compile

2f0b457

fredzqm approved these changes Aug 28, 2025

View reviewed changes

github-project-automation bot moved this from Changes Requested [PR] to Approved [PR] in [Cloud] Extensions + Functions Aug 28, 2025

mbleigh added 2 commits August 28, 2025 13:39

duplicate loadAll

6b06187

Merge branch 'master' into mb/mcp/fdc-compile

7c8af96

mbleigh merged commit 2bde655 into master Aug 28, 2025
48 checks passed

mbleigh deleted the mb/mcp/fdc-compile branch August 28, 2025 20:54

github-project-automation bot moved this from Approved [PR] to Done in [Cloud] Extensions + Functions Aug 28, 2025


		==== TASK INSTRUCTIONS ====

		1. If Data Connect is marked as \`<UNCONFIGURED>\`, first run the \`firebase_init\` tool with \`{dataconnect: {}}\` arguments to initialize it.

feat(mcp): Adds dataconnect_compile tool to MCP server. #8979

feat(mcp): Adds dataconnect_compile tool to MCP server. #8979

Uh oh!

Conversation

mbleigh commented Aug 15, 2025

Uh oh!

gemini-code-assist bot left a comment

Choose a reason for hiding this comment

Summary of Changes

Highlights

Footnotes

Uh oh!

gemini-code-assist bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

fredzqm Aug 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

fredzqm left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

feat(mcp): Adds `dataconnect_compile` tool to MCP server. #8979

feat(mcp): Adds `dataconnect_compile` tool to MCP server. #8979

fredzqm Aug 18, 2025 •

edited

Loading