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

The annotations declare readOnlyHint=true and the description's 'Changes nothing' is consistent with that, so no contradiction. It adds real content beyond the annotations: a yes/no answer with a German-language reason, the specific legal rules (Bauantrag before 1 Nov 1977, change on 1 Jan 2027), price, delivery time and required documents — though some of that overlaps the output schema.

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?

One dense, front-loaded sentence followed by a short safety clause — no filler, and the purpose leads. The single sentence is long and packs output details, legal rules and price into one breath, slightly hurting scannability.

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 an output schema present, the description needn't enumerate return fields, and it still summarizes the verdict shape. The remaining gap: all five parameters are optional, and the description never says how the check behaves when information is missing — a real question for a pre-order eligibility tool.

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 100%, so the five parameters (units, purpose, modernised, year_built, residential_only) are already well documented by the schema itself. The description adds nothing about how those inputs influence the verdict or how partial/unknown inputs are handled, so baseline 3 applies.

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 (checks) on a specific resource (issuance eligibility for a Verbrauchsausweis for a German residential building) and adds the crucial scope 'before any order exists', which separates it from order-side siblings such as start_order or get_status. An agent can route to it without opening any schema.

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?

'before any order exists' clearly places it at the pre-order stage, implying it precedes start_order. It gives the condition for use but does not explicitly name the alternative tools or state when not to use it (e.g. after an order exists, use get_status).

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