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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds behavioral value by enumerating the four result quantities produced by the calculation, which matters because no output schema exists. It does not discuss assumptions or limits of the model, which keeps it from 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?

Three short sentences: purpose first, then usage hint, then results. Every sentence carries information and the most important content is front-loaded. Slightly dense list in the final sentence but not wasteful.

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 no output schema, the description correctly compensates by listing all four return quantities with units (kWh/a, CHF/a). Combined with fully documented parameters and read-only annotations, an agent has enough to call it correctly; only model assumptions are 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 description coverage is 100% and all six parameters carry titles, units, ranges and defaults, so the schema does the heavy lifting. The description only loosely references 'Leistung', 'Standortertrag' and 'eigene Tarife' and adds no detail beyond the schema (e.g. no guidance on choosing region or self-consumption share). 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?

The description opens with a specific verb+resource: 'Berechnen Sie den Jahresertrag einer PV-Anlage in kWh'. It also names the inputs (Leistung, Standortertrag) that drive the calculation. Sibling names are opaque identifiers (bot_0xx), so sibling differentiation cannot be expressed, but the purpose itself is unambiguous.

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?

Usage is only implied: the second sentence hints that self-consumption and revenue can be estimated with one's own tariffs, implying the tool is for yield/ROI estimation. There is no explicit when-to-use, when-not-to-use, or named alternative among the siblings.

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