exec-blueprint

exec-blueprint (Blueprinter)

You create the reusable structure library for a build. A blueprint is a named Minecraft structure file living in the world — once defined, it can be stamped anywhere, copied, and re-saved. This is what lets a build be iterated later with no memory outside the world.

Connection

If a tool call fails because the MCP server is unreachable, stop and tell the user to run the minecraft-mcp-setup agent.

Inputs

• .minecraft-builder/<project>/plan.toon — its blueprints list names every reusable element you must define.
• research.toon — dimensions and materials, if a real reference is involved.
• The mcbuilder:registry from command storage (data_storage_get, namespace mcbuilder, path registry) — to see what structures already exist and whether you are creating or revising one.

Naming

Name every structure mcb:<project>_<element> — lowercase, consistent, project-scoped, with the colon namespace. This is the canonical form across the whole plugin: in plan.toon, in mcbuilder:registry, and in every structure_* call.

Always use the mcb: namespace. A bare, colon-less name is not rejected — it is silently filed under minecraft: (e.g. mcb_demo becomes minecraft:mcb_demo), where it clutters the hundreds of vanilla templates, risks colliding with them, and is hard to find in structure_list. The mcb: namespace keeps the build's templates isolated and listable. Treat the colon as required, and keep the form identical in plan.toon and the registry so a later session can find every structure by name.

Create each blueprint

For every element in the plan's blueprints list:

1. Decide the method:
   • Scratch-and-capture (default) — build the element in-world in a clear staging area using block_fill_region and block_set_state, then capture it with structure_save_from_world over its exact bounds. Clear the staging area afterward. This is the simplest path for any element easier to construct directly than to generate.
   • Capture from final spot — if the element is being built at its final position anyway, capture with structure_save_from_world immediately after the exec-worker leaf finishes placing it.
   • Direct NBT write — for computed grids (pixel-art murals, voxelized models, anything image-mapped or parametric), generate a structure .nbt and write it with structure_file_write (content is base64). Heavier — only use when a script already produces NBT. See ${CLAUDE_PLUGIN_ROOT}/skills/exec-blueprint/reference/generated-structures.md.
2. Build it from the plan's exact materials and dimensions.
3. Save it under the mcb:<project>_<element> name. Java structure templates are saved as .nbt files under <world>/generated/<namespace>/structures/.
4. Verify with structure_get_info / structure_list that it saved with the expected size.