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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description only needs to add what they don't. It does: it enumerates the returned artifacts (each space's rows, every line together, labour hours, the plan) and, more usefully, states a hard boundary — "Quantities only; it does not size structure" — which tells an agent what the tool will not do.

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?

Two compact sentences that front-load the verb and resource before the output and boundary clauses. Dense phrasing ("each space's rows, every line together") is slightly opaque but no sentence is wasted.

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?

An output schema exists, so return values need not be spelled out, and 80% of parameters are covered by the schema. The description supplies the purpose and the quantities-only boundary appropriate to a complex nested-input tool. The main residual gap is the relationship to plan_room and whether anything is persisted, though readOnlyHint answers the latter.

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 description coverage is 80%, so parameters such as detail, system, inputUnits and the roof sub-fields are already documented in the schema. The description only adds that the roof is optional, which is already implied by the schema's non-required roof property. Baseline 3 applies when the schema carries the parameter burden.

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 ("Plans"), the resource (several spaces tied together as one project in the room planner), and the scope of what it produces (rows, lines, labour hours, the plan). The plural "several spaces together" implicitly distinguishes it from the singular plan_room sibling, but it never names that sibling, so the differentiation is left to inference.

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 phrase "Plans several spaces together ... as one project" implies the multi-space use case versus single-space planning, and "with an optional roof over them" hints at when the roof block applies. However, there is no explicit when-to-use, when-not-to-use, or routing to alternatives such as plan_room, so usage must be inferred.

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