FLUX MCP server: generate FLUX images from Claude

To use FLUX from Claude, connect a remote MCP server that runs Black Forest Labs' FLUX image models: fal, Higgsfield, Replicate and Sume each name FLUX on their MCP pages. On Sume's hosted server, generate_image with black-forest-labs/flux.2-pro or black-forest-labs/flux.2-flex makes FLUX.2 stills from a text prompt.

Sume's side comes from its MCP overview, MCP quickstart and Image API docs, the API reference and current catalog code; the other servers come from their own pages. All were read on 2026-09-28. This post is about the FLUX image models, not other software named Flux. The basics page says hosted MCP still works but is not the primary path today; a backend calls POST /v1/images directly.

Which MCP servers can run FLUX?

Four server pages read for this post name FLUX. They differ in which FLUX versions they show and in whose account pays:

How do I add a FLUX MCP server to Claude Code?

For Sume, add the server over HTTP and sign in:

The default sign-in is read-only (mcp:read); paid tools such as generate_image return insufficient_scope until you turn Write on at consent. An API-key session sees the full hosted tool set. For Replicate, its page gives claude mcp add replicate https://mcp.replicate.com/sse --transport sse --scope user, then /mcp to authenticate with a Replicate API token.

claude mcp add --transport http sume https://mcp.sume.com/mcp
claude mcp login sume

What does a FLUX.2 call look like?

Name the model inside payload; without payload.model, generate_image routes to sume/auto and you will not know which family ran. Paid tools need an idempotency_key, and dry_run: true previews admission and cost without submitting:

Send it again without dry_run to submit, then have the agent call jobs_wait and jobs_result. The Image API returns Sume-hosted, signed URLs rather than inline base64, so download the files you keep.

{
  "idempotency_key": "flux-hero-001",
  "dry_run": true,
  "payload": {
    "model": "black-forest-labs/flux.2-pro",
    "prompt": "a glass teapot on a linen tablecloth, soft window light",
    "aspect_ratio": "16:9"
  }
}

What are the limits of FLUX over Sume's MCP?

Read image-models_list or image-models_get before pinning a setting: a model only accepts the values its catalog descriptors list.

• In current catalog code, both FLUX.2 ids take 1:1, 16:9, 9:16, 4:3 and 3:4 among their aspect ratios, and png, jpeg or webp output.
• The docs show FLUX.2 only with a text prompt, so this post treats it as text-to-image. For edits from a reference image, Image editing MCP server covers the models that document them.
• n can ask for up to 10 images, but per-model ceilings are lower; read the n range from the catalog.
• seed and stream are in the schema but not served in v1.

How much does FLUX cost over MCP?

On Sume, generate_image bills the workspace wallet. Image billing is all-or-nothing: a completed generation is billed in full, and a failed or canceled one is not billed. The endpoint pricing lines from GET /v1/images/models are the amount charged, Sume's margin included, so cost_usd × n is what you pay; API pricing has the rate card. Replicate bills for the compute time your models use, and Higgsfield draws on plan credits.