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

The annotation readOnlyHint: true already indicates that the tool has no side effects. The description adds no additional behavioral information (e.g., error handling, authorization requirements, or rate limits), but it does not contradict the annotation. Since the annotation covers the primary safety aspect, a score of 3 is appropriate.

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?

The description is two concise sentences with no redundant information. It packs essential details—the legal basis, the exact thresholds, the time frame (2025 onwards), and the consequence of exceeding the limit—into a compact form. There is no fluff or unnecessary elaboration.

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?

Given that the tool is a simple check with two numeric inputs and no output schema, the description fully covers the necessary information. It states what the tool evaluates and what it returns (whether the regulation applies this and next year, and the immediate termination rule). An agent can confidently invoke this tool without needing additional context.

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?

Both parameters (umsatz_vorjahr and umsatz_laufendes_jahr) have descriptions in the schema, achieving 100% coverage. The tool description explains the significance of the turnover values but does not add extra guidance on parameter units, formats, or edge cases. With full schema coverage, the baseline of 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?

The description clearly states the tool's purpose: to check the two turnover limits of the small business regulation (§19 UStG) as amended from 2025. It specifies the exact thresholds (€25,000 previous year, €100,000 current year) and the output logic (whether the regulation still applies this and next year, and immediate loss of eligibility upon exceeding €100,000). This is a specific verb (prüft) plus a well-defined resource, and it is unique among the sibling tools.

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 description implies when to use the tool (whenever a small business threshold check is needed) but does not explicitly mention when not to use it or name alternative tools. For example, it does not differentiate itself from generic 'pflicht_pruefen' or 'pflichtangaben_pruefen' tools, which could lead to ambiguity in a broader context. However, the high specificity mitigates this.

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