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

Annotations declare readOnlyHint=true, and the description adds context about what the price includes (printing, envelope, postage), which goes beyond the annotation. It does not contradict the read-only nature and provides useful clarity about the calculation scope.

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 concise sentences, front-loaded with a user-facing question and a direct explanation of the result. Every word earns its place with no redundancy.

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?

Given the tool's moderate complexity (6 parameters, no output schema), the description combined with the richly documented schema covers what an agent needs: the return value is explained, and all parameters are described. It lacks only explicit edge-case handling, which is not essential.

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 parameters are well-documented in the schema. The description highlights the two required parameters (paginas, land) but adds no additional semantic value beyond what the schema already provides.

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 calculates the total cost of sending a letter, specifying the inputs (pages, destination) and the output (final price including printing, envelope, and postage). This distinguishes it from sibling tools like 'bestellen' (ordering) and 'landen' (countries).

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 provides clear context: the tool is for pricing a letter mailing, prompting the user for page count and destination. It does not explicitly mention when not to use the tool or alternatives, but the use case is unambiguous enough that an agent can decide between this and other tools.

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