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

With no annotations, the description carries the full behavioral transparency burden. It discloses the calculation formula (perimeter = 2×(width+height)) and the output includes an off-the-shelf size, but it does not state that the operation is a pure read/calculation, nor describe edge-case behavior (e.g., out-of-range inputs). The provided context is helpful but not exhaustive for a calculator with no output schema.

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 sentences, bilingual but compact, with the formula in parentheses. It front-loads the primary purpose and adds the formula and scope in the second sentence. No redundant information or filler; every sentence contributes.

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?

For a relatively simple calculator with no output schema, the description is fairly complete: it states the inputs (sash measurements), the formula, the covered window types, and the output (length plus off-the-shelf size). However, it does not explicitly describe the exact return structure or units, which would be helpful given the lack of an output schema. Still, the description covers the essential aspects well.

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. The description adds value by explaining the relationship between parameters (perimeter formula) and clarifying that 'breite_cm' is the movable part of the sash (already in schema but reinforced in the description). It also maps 'fenstertyp' to tilt-and-turn/roof windows, which aligns with the enum.

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: calculating the required window-seal length for portable air conditioners based on sash dimensions, plus the off-the-shelf size. It specifies the formula and the window types covered (tilt-and-turn and roof windows), distinguishing it from the sibling tools that deal with BTU, wattage, heatwave predictions, etc.

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 gives clear context for when to use this tool (for window seal length from sash measurements, for portable ACs) and what it covers (tilt-and-turn/roof windows). It does not explicitly name alternative tools or exclusions, but the specificity of the calculator's scope makes the usage context apparent.

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