build_from_grid

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds real behavioral context: the exact named meshes/empties produced, the coordinate orientation, and the door/cover height semantics. It does not say whether same-named objects are overwritten or how the operation fails, which keeps it from a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core purpose, then packed with necessary encoding details; almost every clause adds usable information. It runs long and the unit guidance ('cell metres') arrives last as an addendum, but there is little outright waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 10-parameter, no-output-schema creation tool, this covers input encoding, produced artifacts, and downstream verification adequately. The unmentioned origin/floor_thickness/wall_height parameters are the only real gap for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0%, so the description must carry the burden and largely does: it explains layout format, legend structure with kinds, cell units, and ties cover_height/cover_fill/door_height to the 'C' and 'D' characters. However, origin, floor_thickness, and wall_height (as distinct from per-legend height) are never mentioned, leaving part of the 10-param surface undocumented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Block out a level from a text plan') and immediately pins down the input format (one string per row, row 0 at top/+Y, column 0 at left). The character legend and output artifacts ({name}_floor, {name}_walls, {name}_cover, {name}_spawn_1) make it unmistakably distinct from generic siblings like create_primitive or terrain.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly routes the agent to verification tools ('prove it with walkable_map, route, check_passages, sightline_map') and gives a selection heuristic for cell size ('1 for rooms, 0.5 for detail'). It lacks any when-not-to-use or comparison against alternative level-blocking siblings, so it stops short of 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.