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

Annotations already declare readOnly/idempotent/closed-world, so safety is covered; the description adds real behavioral value by enumerating exactly which derived values come back (c_soll, b from a and c_ist, area, perimeter, Δc in mm, actual angle γ). Since no output schema exists, this disclosure is the main source of return-value information.

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, purpose front-loaded, followed by a dense but informative enumeration of returned quantities. The list is long but each item earns its place because there is no output schema to carry it.

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 pure read-only calculation tool with fully documented parameters and no output schema, the description supplies everything an agent needs: inputs, method, use cases, and the complete set of result values. Nothing essential is 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 coverage is 100%, so the baseline is 3, but the description adds genuine semantics by explaining the input→output relationships (c_soll derived from a and b; b derived from a and the measured diagonal; Δc = c_ist − c_soll). It does not explain the region enum, but the schema description already does that adequately.

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?

A specific verb+resource: it computes the 90° right angle and the target diagonal, and names the concrete application domains (Fundamente, Schalungen, PV-Module) plus the underlying method (Satz des Pythagoras). An agent can tell immediately that this is a geometry/right-angle checker rather than a generic calculator.

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?

Clear usage context is given: use it for foundations, formwork and PV module alignment checks with a simple Pythagorean verification. No exclusions or alternative tools are named, but the sibling names are opaque IDs so there is nothing meaningful to route against.

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