tasopen/mcp-alphabanana

English | 日本語
mcp-alphabanana is a Model Context Protocol (MCP) server for generating image assets with Google Gemini. It is built for MCP-compatible clients and agent workflows that need fast image generation, transparent outputs, reference-image guidance, and flexible delivery formats.
Keywords: MCP server, Model Context Protocol, Gemini AI, image generation, FastMCP
Key capabilities:
- Nano Banana 2.1 image generation by default, plus Lite, Flash, and Pro tiers
- Transparent PNG/WebP asset output for web and game pipelines
- Multi-image style guidance with local reference image files
- Flexible file, base64, or combined outputs for agent workflows
Quick Start
Run the MCP server with npx:
Or add it to your MCP configuration:
Set GEMINI_API_KEY before starting the server.
For Claude Desktop,
Download mcp-alphabanana-latest.mcpb, then add it as Extension from Claude Desktop Settings. For Windows, Recommend add 'FileSystem' extension for better local file handling.
Claude Registry
The Claude registry / MCPB package metadata is defined in manifest.json and ships with the static 512x512 icon at images/mcp-alphabanana.png.
Native sharp runtime packages are declared as optional dependencies so .mcpb installs can resolve the correct prebuilt binary on each supported platform without relying on postinstall hooks.
- Stable MCPB URL: https://github.com/tasopen/mcp-alphabanana/releases/latest/download/mcp-alphabanana-latest.mcpb
- Versioned MCPB URL pattern: https://github.com/tasopen/mcp-alphabanana/releases/download/vVERSION/mcp-alphabanana-VERSION.mcpb
- Support: GitHub Issues
MCP Server
This repository provides an MCP server that enables AI agents to generate images using Google Gemini.
It can be used with MCP-compatible clients such as:
- Claude Desktop
- VS Code MCP
- Cursor
Built with FastMCP 3 for a simplified codebase and flexible output options.
Glama MCP Server badge:
Available Tools
generate_image
Generates images using Google Gemini with optional transparency, local reference images, grounding, and reasoning metadata.
For Claude Desktop, prefer outputType=file for medium or large images. base64 and combine responses consume Claude context and can hit the client's size limit. On Windows, use the FileSystem extension to choose a writable absolute outputPath and any local referenceImages paths.
Key parameters:
- prompt (string): description of the image to generate
- model: NanoBanana2.1 (default), Flash3.1 (deprecated), Lite3.1, Flash2.5, Pro3, plus aliases flash, pro
- outputWidth and outputHeight: requested final image size in pixels in normal mode
- noresize + aspectRatio + output_resolution: return Gemini native size without resizing
- output_resolution: 1K, 2K, 4K
- output_format: png, jpg, webp
- outputType: file, base64, combine
- outputPath: required when outputType is file or combine
- transparent: enable transparent PNG/WebP post-processing
- referenceImages: optional array of local reference image files
- grounding_type and thinking_mode: advanced Gemini controls (thinking_mode: minimal / medium / high, default medium)
Model Selection
| Input Model ID | Internal Model ID | Description |
| --- | --- | --- |
| NanoBanana2.1 | gemini-nano-banana-2.1 | **Default.** Google Nano Banana 2.1. Best overall quality, prompt adherence, text rendering, and reference-image handling. 1K/2K/4K, up to 14 reference images. |
| Flash3.1 | gemini-3.1-flash-image | **Deprecated.** Ultra-fast, supports Thinking/Grounding. Google shuts it down on October 29, 2026; requests are rejected from that date. Migrate to NanoBanana2.1. |