Fits Space

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

With no annotations, the description carries the full behavioral burden and does so well: it discloses the trivalent return semantics (true only if it fits under every possible unknown, false only if it can never fit, otherwise null/'unklar'), states that unstated dimensions are never guessed, and specifies which dimensions are measured (door leaf, excluding frame/packaging). The main omission is any note on required authorization or market scoping.

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?

Purpose is front-loaded in the first clause, followed by the interpretive rules an agent actually needs. Sentences are dense but each carries a distinct rule (axis treatment, trivalent logic, dimension convention, margin/weight). Framing headers like 'Give the free space in cm' add slight verbosity without much cost.

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, yet the description still explains the return semantics (fits tri-state plus weight), which is genuinely helpful rather than redundant. Together with the dimension conventions and depth-axis rule, the definition is nearly complete for invocation; only allow_rotation and market scoping remain unexplained.

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 0% across 6 parameters, so the description must compensate and only partially does: it establishes the cm unit for all dimension inputs, explains that omitting max_depth_cm treats that axis as unlimited, and clarifies which physical dimensions of the article are meant. However, allow_rotation (which materially changes fit results and defaults to true) and market are never addressed.

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+resource combination — determining whether an article (identified by SKU) fits a given space — and illustrates the resource with concrete contexts (car load area, doorway, shelf). No sibling tool (search_products, compare_articles, find_article_nearby, delivery_info) overlaps this purpose, so an agent can route unambiguously.

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 opening parenthetical supplies clear usage contexts (car's load area, doorway, shelf), and the instruction to 'leave margin' plus the note that weight is returned 'for your own judgement' tells the agent how to act on the result. There is no explicit when-not guidance or named alternative, but for a single-purpose geometric check this is adequate context.

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