scratch-mcp

MCP server for creating Scratch 3 .sb3 projects programmatically.

Run

python server.py

Tools

• create_project() creates an in-memory Scratch project and returns its project ID.
• add_sprite(project_id, name, svg, ...) adds a sprite with an SVG costume.
• add_backdrop(project_id, svg) adds a stage backdrop.
• add_variable(project_id, target_id, name, default) adds a variable.
• add_block(project_id, target_id, opcode, fields, inputs, ...) adds a Scratch block.
• link_next(project_id, target_id, block_id, next_block_id) links two stack blocks.
• set_input_block(project_id, target_id, block_id, input_name, provider_block_id) connects an output block to an input.
• export_sb3(project_id, output_dir, filename) writes a .sb3 file and returns its path.

Input Values

add_block accepts these input value forms:

• numbers, such as 10 or 1.5, are Scratch numeric literals.
• numeric strings, such as "10" or "-1.5", are also numeric literals.
• lit:<value> creates an explicit text literal.
• var:<name> creates a variable reporter input.
• block:<id> references another block explicitly.
• other strings are kept as block IDs for compatibility with older project scripts.