quantity_takeoff

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the recursive traversal, the unit conventions (m2 one side, m, m3), and notably the inheritance rule that untagged/unpainted entities inherit from their parent group. It stops short of disclosing cost or performance characteristics on large models.

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 action and outcome, then the measurement list, then the inheritance rule — a logical ordering with no filler sentences. The dense colon-and-parenthetical structure is slightly run-on but every clause carries information.

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?

With no output schema, the description usefully enumerates the returned metrics and their units, which is exactly what an agent needs to interpret results. Read-only semantics are covered by annotations. The only gap is the undocumented include_hidden parameter.

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 only 33%, so the description must carry more weight. It does add real meaning for group_by ('by tag or material') and selection_only ('or only the selection'), plus the inheritance nuance that affects grouping. The include_hidden parameter is left undocumented in both schema and description, so the compensation is partial.

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 ('Quantity takeoff: walks the whole model recursively and totals by tag or material') and enumerates exactly what is measured (face area, face count, edge length, volume, instance count). This clearly distinguishes it from sibling listing tools like list_tags, list_components, and selection_info, which enumerate rather than aggregate.

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?

The parenthetical '(or only the selection)' implies the selection_only parameter's purpose and conveys that the default scope is the whole model, which is useful context. However, it never states when an agent should prefer this tool over the sibling listing tools or when to restrict to a selection, so usage is only implied rather than explicit.

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