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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description goes beyond them by disclosing the data source (IBB-Median-Angebotsmiete des Bezirks) and the area-vs-own-values fallback, which is real behavioral context for a calculation tool.

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 dense sentences, output and method front-loaded, no filler. Every clause carries information an agent needs.

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?

Without an output schema the description usefully names the two returned metrics and the reference data used. Minor gaps remain: the yield's unit/format and what happens when area is supplied but price is null.

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 baseline is 3, but the description adds meaning the schema does not: it explains that the three null-able parameters work as an either/or (area lookup vs. supplying own price and rent values). It does not clarify units for the resulting yield.

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 two specific outputs (Brutto-Mietrendite, Kaufpreisfaktor), the asset type (Eigentumswohnungen), the geography (Ortsteil) and the comparison basis (Angebotspreis vs. IBB-Median-Angebotsmiete). This is clearly a computed-metric tool distinct from the retrieval siblings (get_area_prices, get_market_overview), but it never explicitly contrasts itself with them.

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?

"Optional mit eigenen Werten" implies the two operating modes (area-based lookup vs. user-supplied price/rent), which is genuine usage guidance. However there is no explicit statement of when to prefer this tool over get_area_prices or get_market_overview, nor any prerequisite or data-coverage caveat.

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