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

Annotations already declare readOnlyHint, idempotentHint and closed-world, so safety is covered. The description adds value beyond them by disclosing the return payload shape (legal basis, source URL, last-verified date, default assumptions, risk thresholds), which is genuinely useful context. No auth, rate-limit or pagination notes, so not a 5.

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 sentences, the substantive one front-loaded with the return contents and the second carrying the usage cue. Dense and mostly waste-free, though the long parenthetical enumeration is heavy enough to slightly slow scanning.

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?

There is no output schema, so the description carries the burden of describing returns — and it does so thoroughly (per-value legal basis, source URL, verification date, plus assumptions and risk thresholds). For a one-parameter read tool with full annotation coverage, nothing an agent needs to call it correctly is missing.

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 100% and the single parameter's description already documents the YYYY-MM-DD format and today-default in Vienna time. The description's phrase 'on a date' restates the schema without adding format, range or semantics beyond it, so the 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?

Names a specific verb ('List') and a precisely scoped resource (statutory values the engine uses on a date), then enumerates the concrete contents (tax and fee rates, broker caps, MRG cut-off dates, AfA rates, income tax brackets). This is unmistakably a reference/lookup tool and cannot be confused with the sibling mutation tools estimate_acquisition_costs or underwrite_property.

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 closing sentence gives real usage context: 'Use to cite sources or to explain how a number was calculated.' That tells the agent the trigger condition. It stops short of naming alternatives or stating when not to use it, so it does not reach a 5.

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