body_boundary_fill

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

With no annotations, the description carries the full burden and does well: it discloses failure modes (INVALID_PARAMS with nothing changed, FUSION_API_ERROR with rollback) and the resolution path via details.cells center/volume. It does not spell out the side effect on tool bodies when remove_tools is left at its default, which keeps it off 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-loads the one-line purpose, then scope rules, ref provenance, errors, return shape and an example in tight blocks. Dense but nearly every line earns its place; the error sentence is slightly overloaded.

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?

No output schema exists, yet the description supplies the return keys (feature, health, created/modified/removed_bodies), the error contract, and a concrete example. An agent has everything needed to invoke this correctly on the first try.

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 100%, so 3 is the baseline, but the description adds genuine meaning: cell_points selects by containment rather than index, omitted means every cell, tools are entity refs sourced from inspect_query/origin prefixes. Units behavior for the point coordinates is only partly covered.

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?

Names a specific verb+resource (boundary fill producing solids from closed cells) and states the exact precondition — cells enclosed by tool bodies, faces and planes. It is clearly distinguishable from adjacent body tools such as body_combine or body_split.

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?

Explains how cells are selected (points, never index; all cells by default), where refs come from (inspect_query for bodies/faces, origin:*/construction_* for planes) and gives a worked example call. It stops short of explicitly contrasting with sibling tools like body_combine, so it is strong context rather than full when/when-not routing.

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