Image Generation MCP

Multi-provider image generation MCP server built on FastMCP. Generate images from Claude Desktop, Claude Code, or any MCP client using OpenAI, Google Gemini, Stable Diffusion (SD WebUI), or a zero-cost placeholder provider.

Documentation | Config wizard | PyPI | Docker

Features

• Multi-provider: OpenAI (gpt-image-2, gpt-image-1.5, dall-e-3), Google Gemini (gemini-3.1-flash-image, gemini-3-pro-image, gemini-3.1-flash-lite-image), SD WebUI (Stable Diffusion / Forge / reForge), and a zero-cost placeholder for testing.
• Per-model style metadata: every model carries a style_profile (strengths, prompt grammar, lifecycle); list_providers includes a top-level warnings array for deprecated models. See Model Catalog.
• Keyword-based auto-selection: provider="auto" routes by prompt content (text/logo → OpenAI, photoreal/anime → SD WebUI, draft → placeholder).
• CDN-style image transforms: image://{id}/view?format=webp&width=512&crop_x=... resizes / re-encodes / crops on demand without re-generating.
• Hybrid background tasks: long-running SD generations run with task=True (poll for status); short OpenAI calls stream progress in the foreground.
• MCP Apps gallery + viewer: interactive UI surfaces (browse generated images, edit / crop / rotate) for clients that support app: resources.
• Production deployment: Docker (multi-arch), .deb/.rpm with hardened systemd, OIDC + bearer auth, persistent EventStore for HTTP session resumability.

What you can do with it

With this server mounted in an MCP client, you can ask:

• "Generate a coffee mug product photo on a worn oak table, 16:9, no text." Routes to gpt-image-1.5 for typography-aware photorealism.
• "Create three concept-art variations of a cyberpunk alley at dusk." Composes generate_image with provider="sd_webui" and a stylised checkpoint like dreamshaperXL.
• "Crop this image to a 1:1 square centred on the subject and resize to 512px." Uses image://{id}/view?width=512&height=512&crop_x=... resource transforms.
• "Show me my recent generations." Browses the gallery via the image://list resource and the MCP Apps gallery viewer.
• "Save this style as 'cyberpunk-night' so I can apply it to future requests." Uses the style library, whose markdown briefs the LLM interprets per-provider.
• "Replace the background of my last photo with a sunset sky." Uses transform_image with the gallery image_id as a reference (image-to-image via Gemini).

Installation

From PyPI

pip install image-generation-mcp

If you add optional extras via the PROJECT-EXTRAS-START / PROJECT-EXTRAS-END sentinels in pyproject.toml, document them below:

Extra	Includes	Use when
mcp	fastmcp[tasks]>=3.0,<4	Background-task support (task=True), required for long SD generations.
openai	openai>=1.0	Enables the OpenAI provider.
google-genai	google-genai>=1.0	Enables the Gemini provider.
all	fastmcp[tasks] + openai + google-genai	Everything except SD WebUI (which is HTTP-only, no extra needed).

Example: pip install image-generation-mcp[all].

From source

git clone https://github.com/pvliesdonk/image-generation-mcp.git
cd image-generation-mcp
uv sync --all-extras --all-groups

Docker

docker pull ghcr.io/pvliesdonk/image-generation-mcp:latest

A compose.yml ships at the repo root as a starting point. Copy .env.example to .env, edit, and docker compose up -d.

To attach a remote Python debugger (development only; the protocol is unauthenticated), see Remote debugging.

Linux packages (.deb / .rpm)

Download .deb or .rpm packages from the GitHub Releases page. Both install a hardened systemd unit; env configuration is sourced from /etc/image-generation-mcp/env (copy from the shipped /etc/image-generation-mcp/env.example).

Claude Desktop (.mcpb bundle)

Download the .mcpb bundle from the GitHub Releases page and double-click to install, or run:

mcpb install image-generation-mcp-<version>.mcpb

Claude Desktop prompts for required env vars via a GUI wizard, with no manual JSON editing needed.

For manual Claude Desktop configuration and setup options, see Claude Desktop deployment.

Quick start

image-generation-mcp serve                                # stdio transport
image-generation-mcp serve --transport http --port 8000   # streamable HTTP

For library usage (embedding the domain logic without the MCP transport), import from the image_generation_mcp package directly. See the project's domain modules under src/image_generation_mcp/ for entry points.

Server info

The server registers a built-in get_server_info tool (via fastmcp_pvl_core.register_server_info_tool) so operators can confirm the deployed version with a single MCP call. The default response carries server_name, server_version, and core_version. Servers that talk to a remote upstream wire upstream version reporting inside the DOMAIN-UPSTREAM-START / DOMAIN-UPSTREAM-END sentinel in src/image_generation_mcp/server.py; see CLAUDE.md for the wiring pattern.

Configuration

Core environment variables shared across all fastmcp-pvl-core-based services:

Variable	Default	Description
FASTMCP_LOG_LEVEL	INFO	Log level for FastMCP internals and app loggers (DEBUG / INFO / WARNING / ERROR). The -v CLI flag overrides to DEBUG.
FASTMCP_ENABLE_RICH_LOGGING	true	Set to false for plain / structured JSON log output.
IMAGE_GENERATION_MCP_KV_STORE_URL	file:///data/state	Persistent-state backend URL for pvl-core subsystems: file:///path (survives restarts), memory:// (dev/ephemeral).

Domain-specific variables go below under Domain configuration.

Authentication

Callers authenticate via a bearer token or OIDC (mutually exclusive). See the Authentication guide for setup, mapped multi-subject tokens, OIDC, and troubleshooting.

Post-scaffold checklist

After copier copy and gh repo create --push:

1. Fill in the DOMAIN blocks (every section marked with a DOMAIN sentinel comment) in this README and in CLAUDE.md.
2. Configure GitHub secrets (see below).
3. Install dev + docs tooling: uv sync --all-extras --all-groups.
4. Install pre-commit hooks: uv run pre-commit install.
5. Run the gate locally: uv run pytest -x -q && uv run ruff check --fix . && uv run ruff format . && uv run mypy src/ tests/.
6. Push the first commit. CI should be green.

GitHub secrets

CI workflows reference three repository secrets. Configure them via Settings → Secrets and variables → Actions or with gh secret set:

Secret	Used by	How to generate
RELEASE_TOKEN	release.yml, copier-update.yml	Fine-grained PAT at https://github.com/settings/personal-access-tokens/new with contents: write and pull_requests: write (the copier-update cron opens PRs). Scoped to this repo.
CODECOV_TOKEN	ci.yml	https://codecov.io: sign in with GitHub and add the repo. The upload token is on the repo settings page.
CLAUDE_CODE_OAUTH_TOKEN	claude.yml, claude-code-review.yml	Run claude setup-token locally and paste the result.

gh secret set RELEASE_TOKEN
gh secret set CODECOV_TOKEN
gh secret set CLAUDE_CODE_OAUTH_TOKEN

GITHUB_TOKEN is auto-provided; no action needed.

Local development

The PR gate (matches CI):

uv run pytest -x -q                                  # tests
uv run ruff check --fix . && uv run ruff format .    # lint + format
uv run mypy src/ tests/                              # type-check

Pre-commit runs a subset of the gate on each commit; see .pre-commit-config.yaml for details, or CLAUDE.md for the full Hard PR Acceptance Gates.

Troubleshooting

Moving a scaffolded project

uv sync creates .venv/bin/* scripts with absolute shebangs pointing at the venv Python. If you move the repo after scaffolding (mv /old/path /new/path), uv run pytest fails with ModuleNotFoundError: No module named 'fastmcp' because the stale shebang resolves to a different interpreter than the venv's site-packages.

Fix:

rm -rf .venv
uv sync --all-extras --all-groups

uv run python -m pytest also works as a one-shot workaround (bypasses the stale entry-script shim).

uv.lock refresh after copier update

When copier update introduces new dependencies (such as a new extra added to pyproject.toml.jinja), CI runs uv sync --frozen which fails against a stale lockfile. Run uv lock locally and commit the refreshed uv.lock alongside accepting the copier-update PR.

Links

• Documentation
• llms.txt
• FastMCP
• fastmcp-pvl-core

Domain configuration

All domain environment variables use the IMAGE_GENERATION_MCP_ prefix.

Core

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_SCRATCH_DIR	~/.image-generation-mcp/images/	No	Directory for saved generated images.
IMAGE_GENERATION_MCP_READ_ONLY	true	No	Hide write-tagged tools (generate_image). Set to false to enable generation.
IMAGE_GENERATION_MCP_DEFAULT_PROVIDER	auto	No	Default provider: auto, openai, gemini, sd_webui, placeholder.

Providers

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_OPENAI_API_KEY	(none)	No	OpenAI API key; enables OpenAI provider when set.
IMAGE_GENERATION_MCP_GOOGLE_API_KEY	(none)	No	Google API key with Gemini access; enables Gemini provider when set.
IMAGE_GENERATION_MCP_SD_WEBUI_HOST	(none)	No	SD WebUI URL (http://localhost:7860); enables SD WebUI provider when set. Deprecated alias: A1111_HOST.
IMAGE_GENERATION_MCP_SD_WEBUI_MODEL	(none)	No	SD WebUI checkpoint name for preset detection and override. Deprecated alias: A1111_MODEL.

Authentication

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_BEARER_TOKEN	(none)	No	Static bearer token; enables bearer auth when set.
IMAGE_GENERATION_MCP_BASE_URL	(none)	No	Public base URL for OIDC and the capability-link transfer routes (https://mcp.example.com). Also enables create_download_link / create_upload_link and the /transfer/{token} endpoint on HTTP transports.
IMAGE_GENERATION_MCP_OIDC_CONFIG_URL	(none)	No	OIDC discovery endpoint URL.
IMAGE_GENERATION_MCP_OIDC_CLIENT_ID	(none)	No	OIDC client ID.
IMAGE_GENERATION_MCP_OIDC_CLIENT_SECRET	(none)	No	OIDC client secret.
IMAGE_GENERATION_MCP_OIDC_JWT_SIGNING_KEY	ephemeral	Yes on Linux/Docker	JWT signing key.
IMAGE_GENERATION_MCP_OIDC_AUDIENCE	(none)	No	Expected JWT audience claim.
IMAGE_GENERATION_MCP_OIDC_REQUIRED_SCOPES	openid	No	Comma-separated required scopes.
IMAGE_GENERATION_MCP_OIDC_VERIFY_ACCESS_TOKEN	false	No	Verify access token as JWT instead of id token.

Cost control & performance

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_PAID_PROVIDERS	openai	No	Comma-separated paid provider names. Triggers an elicitation cost-confirmation on capable clients. Gemini is omitted by default (generous free tier); add gemini if you rely on quality="hd", which bills thinking tokens. Set to empty to disable.
IMAGE_GENERATION_MCP_TRANSFORM_CACHE_SIZE	64	No	Max cached transforms. Set to 0 to disable caching.

Reference image input (transform_image)

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_ALLOW_LOCAL_FILE_INPUT	false	No	Enable local filesystem paths as transform_image reference images. Security: grants callers server-filesystem read access via path; enable only for trusted callers or local single-user deployments.
IMAGE_GENERATION_MCP_MAX_INPUT_IMAGE_BYTES	20971520	No	Per-reference maximum byte size for input images (default 20 MiB).
IMAGE_GENERATION_MCP_FETCH_TIMEOUT_S	30.0	No	HTTP fetch timeout in seconds, used when fetching remote image URLs.

Capability-link transfer (HTTP downloads/uploads)

The create_download_link / create_upload_link tools and the /transfer/{token} route register only on an HTTP or SSE transport with BASE_URL set, and store link tokens in IMAGE_GENERATION_MCP_KV_STORE_URL. The knobs below tune link lifetime and upload limits.

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_TRANSFER_TTL_DEFAULT_S	3600	No	Link lifetime (seconds) when the caller omits ttl_s (1 hour).
IMAGE_GENERATION_MCP_TRANSFER_TTL_MAX_S	86400	No	Ceiling (seconds); a caller-requested ttl_s is clamped to this (24 hours).
IMAGE_GENERATION_MCP_TRANSFER_GRACE_TTL_S	60	No	Post-success grace window (seconds) for a stalled transfer to retry.
IMAGE_GENERATION_MCP_TRANSFER_LEASE_S	60	No	Reclaim window (seconds) for an in-flight reservation from a crashed handler.
IMAGE_GENERATION_MCP_TRANSFER_MAX_UPLOAD_BYTES	104857600	No	Per-upload size cap in bytes for create_upload_link POSTs (100 MiB).

Server identity

Variable	Default	Required	Description
IMAGE_GENERATION_MCP_SERVER_NAME	image-generation-mcp	No	Server name shown to MCP clients.
IMAGE_GENERATION_MCP_INSTRUCTIONS	(computed)	No	System instructions for LLM context.
IMAGE_GENERATION_MCP_HTTP_PATH	/mcp	No	HTTP endpoint mount path.
IMAGE_GENERATION_MCP_APP_DOMAIN	(auto)	No	MCP Apps widget sandbox domain. Auto-computed from BASE_URL for Claude; override for other hosts.

Domain-config fields are composed inside src/image_generation_mcp/config.py between the CONFIG-FIELDS-START / CONFIG-FIELDS-END sentinels; env reads go through fastmcp_pvl_core.env(_ENV_PREFIX, "SUFFIX", default) so naming stays consistent.

For the full MCP tool / resource / prompt surface and per-provider setup notes, see the documentation site.

Key design decisions

• Multi-provider with capability discovery, not feature flags. Each provider's discover_capabilities() reports its actual supported aspect ratios / qualities / formats / negative-prompt support at startup; routing logic asks the capability surface, not a hard-coded enum. New providers slot in by satisfying the protocol, with no router edits needed. (See docs/decisions/0001-…, 0002-…, 0007-….)
• Per-model style_profile metadata, surfaced via list_providers. Closed-list providers (OpenAI, Gemini, placeholder) use exact-key lookup; SD WebUI uses a regex-ordered pattern table. Profiles include lifecycle flags (current / legacy / deprecated) and feed an auto-built top-level warnings array. (See docs/decisions/0009-….)
• Hybrid background tasks. Short calls (OpenAI ~5 s) stream progress in-line; long calls (SD WebUI 30-180 s) run as background tasks with check_generation_status polling; clients pick the mode via task=True. (See docs/decisions/0005-….)
• Image asset model: content-addressed registry + sidecar JSON metadata + on-demand transforms. Generated images keep their full-resolution original; image://{id}/view?format=webp&width=512&crop_x=… resources do format conversion / resize / crop on demand without re-generating. Transforms are cached. (See docs/decisions/0006-….)
• Style library. User-saved markdown briefs (with YAML frontmatter for tags / aspect ratio / quality) that the LLM interprets per-provider, not copy-pasted verbatim. Distinct from per-model style_profile: style library is the brief; style_profile describes the model. (See docs/decisions/0008-… and 0009-… for disambiguation.)
• Composes fastmcp_pvl_core.ServerConfig, never inherits. Domain config goes between CONFIG-FIELDS-START / CONFIG-FIELDS-END sentinels; env reads route through fastmcp_pvl_core.env(...) to keep prefix naming consistent.