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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so safety is covered. The description adds genuine value by enumerating the four computed outputs (s_k, mu_1, q_k, and mass in kg/m²) since no output schema exists. It does not disclose that all parameters have defaults or how the region switch alters the calculation, which keeps it below 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, front-loaded with the method and inputs, followed by the outputs with units. Nothing is redundant or padded.

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 five-parameter, all-optional calculation tool with no output schema, the description covers purpose and return values well. The remaining gap is the unaddressed region switch, which determines whether SIA 261 or DIN VDE rules apply and materially changes the result.

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 schema itself documents all five parameters, making 3 the baseline. The description reinforces four of the five inputs but says nothing about the region parameter — the most confusing one, whose enum mixes a national standard choice (DIN VDE vs NIN/SIA) with unrelated marketplace references — so it does not resolve the ambiguity the schema leaves.

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 names a specific computation and standard: characteristic snow load on roofs per SIA 261, derived from reference altitude, roof pitch, and exposure/temperature coefficients. It is far from a restatement of the title. It loses a point because it presents the tool as Switzerland-only while the schema exposes a region parameter defaulting to DE (Germany/Austria, DIN VDE), leaving the actual scope ambiguous.

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?

No guidance on when to select this tool versus alternatives, no statement of prerequisites, and no note that all five inputs are optional with typical defaults. The only implicit cue is the SIA 261 standard, which an agent must interpret on its own.

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