# GTM MCP Server

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---
> [!IMPORTANT]  
> The hosted instance at https://mcp.gtmeditor.com will be shut down on November 30, 2026. See [#139](https://github.com/paolobietolini/gtm-mcp-server/issues/139) for details. Thanks to everyone who used it!

---
GTM MCP Server connects MCP clients to the Google Tag Manager API. It can
inspect containers, create and update workspace entities, create versions, and
publish a selected version after explicit confirmation.

Use the hosted server at:

```text
https://mcp.gtmeditor.com
```


The server supports browser-based Google OAuth for individual users and
service-account authentication for self-hosted automation.

## Project status

| Item | Current state |
|---|---|
| Version in `server.json` | `1.12.3` |
| Transport | MCP Streamable HTTP |
| Runtime tools | 64 GTM tools by default; 94 with `GTM_TOOL_GROUPS=all`, plus 2 utility tools |
| MCP resources | 8 resource definitions |
| MCP prompts | 6 prompts |
| Official GTM API coverage | 101 of 106 methods |
| Hosted endpoint | `https://mcp.gtmeditor.com` |

The project implements 101 methods from Google's 106-method GTM v2 discovery surface. The five `accounts.user_permissions` methods are intentionally excluded because granting and revoking GTM access are security-related and it shouldn't be manager by an LLM.

## Connect an MCP client

Add the hosted URL as a remote HTTP MCP server. The client should discover the OAuth metadata, open Google sign-in, and reconnect with the issued bearer
token.

### Claude Code

```bash
claude mcp add --transport http gtm https://mcp.gtmeditor.com
```

### Gemini CLI

```bash
gemini mcp add --transport http gtm https://mcp.gtmeditor.com
```

Gemini CLI can also use this `settings.json` entry:

```json
{
  "mcpServers": {
    "gtm": {
      "httpUrl": "https://mcp.gtmeditor.com"
    }
  }
}
```

### Cursor

Add the following to `.cursor/mcp.json`:

```json
{
  "mcpServers": {
    "gtm": {
      "url": "https://mcp.gtmeditor.com"
    }
  }
}
```

### ChatGPT, Codex, and Claude web

Add a custom or remote MCP connection in the client and use
`https://mcp.gtmeditor.com` as the server URL. Product menus change more often
than this server, so refer to the client's current MCP connection instructions
if the label differs.

After connecting, try:

```text
List my GTM accounts, containers, and workspaces. Do not make changes.
```

The Google account used during OAuth determines which GTM accounts the server
can access.

## Typical workflow

1. Call `list_accounts`, `list_containers`, and `list_workspaces` to discover
   IDs. Do not guess IDs.
2. Inspect the workspace with list/get tools or the `audit_container` prompt.
3. Create or update tags, triggers, variables, templates, clients, or
   transformations in the selected workspace.
4. Call `get_workspace_status` and resolve conflicts before versioning.
5. Call `create_version` to snapshot the workspace.
6. Inspect the saved version with `get_version`.
7. Call `publish_version` with `confirm: true` only when the selected version
   is ready to go live.
8. Verify the published state with `get_live_version`.

Example requests:

- "Audit this workspace for duplicate tags and unused triggers."
- "Create a GA4 purchase event tag, but do not publish it."
- "Show the difference between the latest saved version and the live version."
- "Generate a Markdown tracking plan from this workspace."
- "Import the iubenda template from the Community Template Gallery."

## Tools

All GTM tools use the authenticated Google identity from the current MCP
request. Inputs and outputs are structured JSON.

### Utility

| Tool | Purpose |
|---|---|
| `ping` | Test MCP connectivity |
| `auth_status` | Check whether the current request is authenticated |

### Accounts and containers

| Tool | Purpose |
|---|---|
| `list_accounts` | List accessible GTM accounts |
| `update_account` | Rename an account |
| `list_containers` | List containers and their public IDs and settings |
| `lookup_container` | Find a container by destination ID or GTM public tag ID |
| `get_container_snippet` | Get a web install snippet or server-container configuration |
| `create_container` | Create a web, app, AMP, or server container |
| `update_container` | Rename a container while preserving its other settings |
| `delete_container` | Permanently delete a container; requires `confirm: true` |
| `combine_containers` | Merge a source container into a target; requires `confirm: true` |
| `move_tag_id` | Move a tag ID into a new container; requires confirmation and terms acceptance |

### Workspaces

| Tool | Purpose |
|---|---|
| `list_workspaces` | List workspaces in a container |
| `create_workspace` | Create a workspace |
| `get_workspace` | Get workspace metadata and its current fingerprint |
| `update_workspace` | Update selected workspace fields |
| `delete_workspace` | Delete a workspace; requires `confirm: true` |
| `quick_preview_workspace` | Compile an ephemeral preview without saving or publishing |
| `get_workspace_status` | Show pending changes and merge conflicts |
| `bulk_update_workspace` | Apply multiple entity changes; requires `confirm: true` |
| `resolve_workspace_conflict` | Replace a conflict with a resolved entity; requires `confirm: true` |
| `sync_workspace` | Synchronize with the latest container version; requires `confirm: true` |

Bulk update and conflict resolution accept raw GTM Entity JSON so every entity
type supported by the official API remains available.

### Tags

| Tool | Purpose |
|---|---|
| `list_tags` | List workspace tags |
| `get_tag` | Get complete tag details |
| `create_tag` | Create a tag |
| `update_tag` | Update a tag with fingerprint-based concurrency control |
| `delete_tag` | Delete a tag; requires `confirm: true` |

### Triggers

| Tool | Purpose |
|---|---|
| `list_triggers` | List workspace triggers |
| `get_trigger` | Get complete trigger details |
| `create_trigger` | Create a trigger |
| `update_trigger` | Update a trigger with fingerprint-based concurrency control |
| `delete_trigger` | Delete a trigger; requires `confirm: true` |

For `update_trigger`, omit `filterJson`, `customEventFilterJson`,
`autoEventFilterJson`, or `parameterJson` to preserve the current field. Pass
the JSON string `"[]"` to clear a field, or a non-empty JSON array to replace
it. For click, link-click, and form-submission triggers, use `filterJson` because
GTM drops `autoEventFilter` for those trigger types.

### Variables

| Tool | Purpose |
|---|---|
| `list_variables` | List workspace variables |
| `get_variable` | Get complete variable details |
| `create_variable` | Create a variable |
| `update_variable` | Update a variable with fingerprint-based concurrency control |
| `delete_variable` | Delete a variable; requires `confirm: true` |

### Folders and built-in variables

| Tool | Purpose |
|---|---|
| `list_folders` | List workspace folders |
| `get_folder` | Get complete folder metadata |
| `create_folder` | Create a folder |
| `update_folder` | Update a folder with fingerprint protection |
| `delete_folder` | Delete a folder; requires `confirm: true` |
| `get_folder_entities` | List tags, triggers, and variables assigned to a folder |
| `move_entities_to_folder` | Move tags, triggers, and variables; requires `confirm: true` |
| `revert_folder` | Discard workspace folder changes; requires `confirm: true` |
| `list_built_in_variables` | List enabled built-in variables |
| `enable_built_in_variables` | Enable built-in variable types |
| `disable_built_in_variables` | Disable built-in variable types; requires `confirm: true` |

Use `revert_workspace_entity` to discard changes to a built-in variable.

### Zones

| Tool | Purpose |
|---|---|
| `list_zones` | List all zones across every result page |
| `get_zone` | Get boundary, child-container, and type-restriction configuration |
| `create_zone` | Create a workspace zone |
| `update_zone` | Update selected fields with fingerprint concurrency control |
| `delete_zone` | Delete a zone; requires `confirm: true` |

Use `revert_workspace_entity` to discard changes to a zone.

### Environments

The `environments` tool group is optional. Enable it with
`GTM_TOOL_GROUPS=all` or add `environments` to an explicit group list.

| Tool | Purpose |
|---|---|
| `list_environments` | List all container environments across every result page |
| `get_environment` | Get environment configuration and authorization metadata |
| `create_environment` | Create a user environment |
| `update_environment` | Update selected fields with fingerprint concurrency control |
| `reauthorize_environment` | Rotate the authorization code; requires `confirm: true` |
| `delete_environment` | Delete a user environment; requires `confirm: true` |

The Live and Latest environments are managed by GTM. Creation and deletion
apply to user environments; GTM permits URL and debug updates on other types.

### Destinations and Google tag configurations

These tools are in the optional `destinations` and `gtag` groups.

| Tool | Purpose |
|---|---|
| `list_destinations` | List Google tag destinations linked to a container |
| `get_destination` | Get a destination by its link ID |
| `link_destination` | Move a destination to a container; requires `confirm: true` |
| `list_google_tag_configs` | List Google tag configurations in a workspace |
| `get_google_tag_config` | Get a Google tag configuration |
| `create_google_tag_config` | Create a Google tag configuration |
| `update_google_tag_config` | Update a configuration with fingerprint protection |
| `delete_google_tag_config` | Delete a configuration; requires `confirm: true` |

Container combine, tag-ID move, and destination link operations do not copy or
enable user permissions. Account permission management remains outside the
current parity target.

### Custom templates

| Tool | Purpose |
|---|---|
| `list_templates` | List custom templates |
| `get_template` | Get template metadata and template code |
| `create_template` | Create a custom template from `.tpl` code |
| `update_template` | Update template code |
| `delete_template` | Delete an unused template; requires `confirm: true` |
| `import_gallery_template` | Import a Community Template Gallery template |
| `get_tag_templates` | Return compact GA4 and Custom HTML input examples |
| `get_trigger_templates` | Return compact trigger input examples |

The full JSON examples live in the
`gtm://best-practices/tool-input-formats` resource so every tool listing does
not repeat them.

### Server-side containers

| Tool | Purpose |
|---|---|
| `list_clients` | List server-container clients |
| `get_client` | Get a client |
| `create_client` | Create a client |
| `update_client` | Update a client |
| `delete_client` | Delete a client; requires `confirm: true` |
| `list_transformations` | List transformations |
| `get_transformation` | Get a transformation |
| `create_transformation` | Create a transformation |
| `update_transformation` | Update a transformation |
| `delete_transformation` | Delete a transformation; requires `confirm: true` |

Use `revert_workspace_entity` to discard changes to a client or transformation.

### Versions and publication

| Tool | Purpose |
|---|---|
| `list_versions` | List all saved version headers across every result page |
| `get_latest_version_header` | Get the latest saved header, which may differ from live |
| `get_version` | Get a saved version and its complete entity collections |
| `get_live_version` | Get the currently published version and its entities |
| `create_version` | Create a version from a conflict-free workspace |
| `publish_version` | Publish a selected version; requires `confirm: true` |
| `update_version` | Update a saved version's name or description |
| `delete_version` | Soft-delete a version; requires `confirm: true` |
| `undelete_version` | Restore a soft-deleted version; requires `confirm: true` |
| `set_latest_version` | Make a version Latest without publishing; requires `confirm: true` |

### Workspace reverts

| Tool | Purpose |
|---|---|
| `revert_workspace_entity` | Discard workspace changes to a built-in variable, client, tag, template, transformation, trigger, variable, or zone; requires `confirm: true` |

The tool fetches the current entity fingerprint before calling the matching
official revert method. A successful result can have `existsAfterRevert: false`
when the entity does not exist in the latest container version.

## Safety model

- Delete operations, publication, and disabling built-in variables require
  `confirm: true`.
- Update operations fetch the current resource fingerprint and use Google's
  optimistic concurrency checks.
- `create_version` first checks that the workspace has changes and no merge
  conflicts.
- Read tools distinguish latest saved state from published live state.
- Google API errors are mapped to clearer not-found, permission, conflict, and rate-limit failures. Retryable API failures use bounded backoff.
- MCP request bodies are limited to 5 MiB. OAuth and dynamic registration
  endpoints have stricter rate and body limits.

Most entity edits affect a workspace and are not live until a version is
published. Account and container operations act directly on those resources.
Always review the target IDs and the generated version before publication.

## Resources

The server exposes two concrete resources and six URI templates:

| URI | Content |
|---|---|
| `gtm://accounts` | Accessible accounts |
| `gtm://accounts/{accountId}/containers` | Containers |
| `gtm://accounts/{accountId}/containers/{containerId}/workspaces` | Workspaces |
| `gtm://accounts/{accountId}/containers/{containerId}/workspaces/{workspaceId}/tags` | Tags |
| `gtm://accounts/{accountId}/containers/{containerId}/workspaces/{workspaceId}/triggers` | Triggers |
| `gtm://accounts/{accountId}/containers/{containerId}/workspaces/{workspaceId}/variables` | Variables |
| `gtm://best-practices` | Best-practice topic index |
| `gtm://best-practices/{topic}` | One embedded guidance document |

Best-practice topics include naming and organization, safe edits, GA4 and
consent, server-side containers, and detailed tool input formats.

## Prompts

| Prompt | Purpose |
|---|---|
| `audit_container` | Review tags, triggers, and variables for quality problems |
| `generate_tracking_plan` | Build a Markdown tracking plan from a workspace |
| `suggest_ga4_setup` | Recommend a GA4 structure from stated goals |
| `find_gallery_template` | Guide Community Gallery discovery and import |
| `best_practices_review` | Score a workspace against embedded guidance |
| `plan_safe_edit` | Produce a staged edit/version/publish plan |

Prompts prepare context and instructions for the model. They do not bypass tool authentication or mutation safeguards.

## Authentication

### Hosted OAuth

The hosted server implements MCP OAuth discovery and Google authorization. It
supports PKCE, Dynamic Client Registration, Client ID Metadata Documents,
authorization-server metadata, and protected-resource metadata.

The server never receives a Google password. It receives Google OAuth tokens
after consent. A self-hosted operator can keep issued MCP and Google tokens
across restarts by setting `TOKEN_STORE_PATH`; without that setting they remain in memory and disappear when the process stops.

Expired MCP access tokens can be renewed transparently while their Google
refresh credentials remain valid. `AUTH_AUTO_REFRESH_MAX_AGE` limits how long
one bearer can be silently extended; its default is seven days.

### Service-account mode

Service-account mode gives every holder of one server API key the GTM access
granted to the configured Google service account.

1. Create a Google service account.
2. Add its email address to the required GTM account with only the permissions
   it needs.
3. Set a strong `SERVICE_ACCOUNT_API_KEY` on this server.
4. Set `GOOGLE_SERVICE_ACCOUNT_KEY_JSON` to the key JSON, or use Application
   Default Credentials on Google Cloud.
5. Configure the MCP client to send
   `Authorization: Bearer <SERVICE_ACCOUNT_API_KEY>`.

OAuth and service-account mode can run together. Requests with the configured
API key use the service account; OAuth users keep their own Google identity and GTM permissions.

## Self-hosting

### Requirements

- Go 1.26 or Docker
- A Google Cloud project with the Tag Manager API enabled
- A Google OAuth web client for user OAuth, or a Google service account for S2S
- HTTPS and a stable public URL for remote OAuth deployments

### Google OAuth setup

Create an OAuth 2.0 Web application in Google Cloud and add this authorized
redirect URI:

```text
https://your-host.example/oauth/callback
```

The scheme and host must match `BASE_URL` exactly. For local development, use:

```text
http://localhost:8080/oauth/callback
```

### Run from source

```bash
git clone https://github.com/paolobietolini/gtm-mcp-server.git
cd gtm-mcp-server

cat > .env <<'EOF'
BASE_URL=http://localhost:8080
GOOGLE_CLIENT_ID=your-client-id.apps.googleusercontent.com
GOOGLE_CLIENT_SECRET=your-client-secret
TOKEN_STORE_PATH=./data/tokens.json
EOF

go run .
```

The repository reads `.env` and then `.env.local`; `.env.local` overrides
`.env`. Both are ignored by Git.

### Run with Docker

```bash
docker build -t gtm-mcp-server .

docker run --rm \
  --name gtm-mcp-server \
  -p 8080:8080 \
  --env-file .env \
  -v gtm-mcp-tokens:/data \
  gtm-mcp-server
```

When using the named volume, set `TOKEN_STORE_PATH=/data/tokens.json` in
`.env`.

### Configuration

| Variable | Default | Purpose |
|---|---|---|
| `PORT` | `8080` | HTTP listen port |
| `BASE_URL` | `http://localhost:8080` | Canonical public URL used by OAuth metadata and callbacks |
| `DASHBOARD_ENABLED` | `false` | Expose the public connection setup page at `/dashboard/` |
| `GOOGLE_CLIENT_ID` | empty | Google OAuth web-client ID |
| `GOOGLE_CLIENT_SECRET` | empty | Google OAuth web-client secret |
| `ACCESS_TOKEN_TTL` | `8h` | Lifetime of MCP access tokens |
| `AUTH_AUTO_REFRESH_MAX_AGE` | `168h` | Maximum silent-renewal chain age |
| `TOKEN_STORE_PATH` | empty | Optional persisted token-store file |
| `SERVICE_ACCOUNT_API_KEY` | empty | Bearer API key that enables S2S mode |
| `GOOGLE_SERVICE_ACCOUNT_KEY_JSON` | empty | Service-account JSON; omit when ADC is available |
| `ALLOWED_HOSTS` | empty | Additional trusted hosts for Docker/internal URL resolution |
| `TRUST_PROXY` | `false` | Trust the rightmost `X-Forwarded-For` hop for rate limiting |
| `LOG_LEVEL` | `info` | Set `debug` for additional structured logs |
| `GTM_TOOL_GROUPS` | current groups | Comma-separated tool families advertised through MCP |

If OAuth and service-account credentials are both absent, the server starts in
open mode. Use open mode only for isolated local development.

`TRUST_PROXY=true` is appropriate only when a trusted reverse proxy overwrites
or appends `X-Forwarded-For`. The implementation uses the rightmost value. With
multiple proxy hops, configure and test the trust boundary before relying on
per-client rate limits.

`ALLOWED_HOSTS` is a comma-separated allowlist used when the same server is
reached through trusted internal Docker hostnames. Do not add arbitrary public hosts.

`GTM_TOOL_GROUPS` controls schema size for clients that need only part of the
API. Available groups are `accounts`, `workspaces`, `tags`, `triggers`,
`variables`, `folders`, `builtins`, `zones`, `templates`, `server`, `guidance`,
`environments`, `destinations`, `gtag`, `container-admin`, `folder-admin`, and
`workspace-admin`, `version-admin`, and `reverts`. Leaving it unset preserves
the established 64-tool surface. New parity groups are opt-in. Use `all` to
include every current and future parity family, or select a subset:

```text
GTM_TOOL_GROUPS=accounts,workspaces,tags,triggers,variables
```

The two connection utility tools remain available regardless of this setting.

### Optional setup dashboard

Set `DASHBOARD_ENABLED=true` and restart the server to expose `/dashboard/`.
The page shows the canonical MCP endpoint, server version, authentication setup status, and connection instructions. It is disabled by default.

The dashboard is public when enabled. It deliberately excludes tokens, sessions, account names, container data, and other GTM content. It reports server configuration only and does not verify the visitor's Google session.

## Releases and deployment

`server.json` is the source of truth for the runtime version. It is embedded in the Go binary and returned by `/health`; there is no second version constant in Go code.

To publish a release:

1. Update `server.json`.
2. Commit the release changes.
3. Push a matching tag such as `v1.11.0`.

The release workflow rejects a tag that does not match `server.json`, creates
cross-platform archives with GoReleaser, and then deploys the tagged source to the production VPS. The deployment uses the GitHub environment
`auto-deployment` and expects these secrets:

- `SSH_PRIVATE_KEY`
- `VPS_KNOWN_HOSTS`
- `VPS_HOST`
- `VPS_USER`

The workflow preserves server-only `.env`, `docker-compose.yml`, and token data, keeps a rollback image, rebuilds the service, and waits until `/health`reports the expected version.

Recent commits on `main` can be newer than the latest tagged release. Check the [release page](https://github.com/paolobietolini/gtm-mcp-server/releases) when you need a reproducible published artifact.

## Development

```bash
go test ./... -count=1
go vet ./...
staticcheck ./...
go run ./cmd/tool-schema-report
go run ./cmd/tool-schema-report -groups tags,zones
```

The schema report prints the GTM tool count, serialized `tools/list` size, token
estimate, and largest definitions. The default GTM tool surface serializes to
78,734 bytes for 64 tools. A regression test enforces an 80,000-byte ceiling so
new parity work does not silently consume unlimited model context. The `all`
group exposes 94 GTM tools and serializes to 115,748 bytes.

Pull requests run `govulncheck`, `gosec`, Gitleaks, Trivy, `staticcheck`, and
CodeQL. Request-level GTM tests use local fake Google endpoints. Mutating live
tests must use a disposable container and clean up their entities.

See [ARCHITECTURE.md](ARCHITECTURE.md) for package boundaries, request flow,
authentication internals, token persistence, and security invariants.

For a deep dive into the Google Tag Manager MCP server, read the [Deep Wiki](https://deepwiki.com/paolobietolini/gtm-mcp-server).


## Additional context

- [`llms.txt`](llms.txt) is served at
  [`https://mcp.gtmeditor.com/llms.txt`](https://mcp.gtmeditor.com/llms.txt).
- [`skills/gtm-mcp/gtm-mcp.md`](skills/gtm-mcp/gtm-mcp.md) contains a Claude
  Code skill with workflow guidance.
- [`examples/gtm_agent.py`](examples/gtm_agent.py) demonstrates a programmatic
  MCP client.
- [Google Tag Manager API v2 reference](https://developers.google.com/tag-platform/tag-manager/api/reference/rest)
- [Model Context Protocol](https://modelcontextprotocol.io/)

## License

BSD 3-Clause. See [LICENSE](LICENSE).

Maintained by [Paolo Bietolini](https://github.com/paolobietolini).