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

Annotations already declare readOnly, idempotent and closed-world, so the description doesn't need to carry the safety burden. It does add real value by enumerating the four returned metrics in the absence of an output schema. It does not disclose the underlying sizing method or assumptions (e.g., days of autonomy), which would have pushed this higher.

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, front-loaded with the purpose and followed by the output quantities; nothing is wasted. The dense result list is slightly terse but still readable.

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 naming each returned value with units. For a purely computational, annotated, fully described parameter set this is nearly complete; only the calculation 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%: every parameter has a title, range, default, and the enum values are explained (including DE = DIN VDE, CH = NIN/SIA). The description adds no parameter-level meaning beyond the listed results, 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?

States a specific verb and resource: sizing a PV battery storage (usable and nominal capacity) from evening/night consumption, and enumerates the result quantities. Very clear about what the tool produces, but the opaque name bot_047 gives no clue and the description does not (and cannot, given opaque siblings) differentiate it from the other bot_* 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?

Usage is implied by the input set (annual consumption, PV power, night fraction), so an agent can infer this is a storage-sizing calculator. However, there is no explicit when-to-use, no prerequisites, and no mention of the alternative tools that presumably cover other PV calculations.

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