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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds context beyond that: the preview is free, it draws on data from 1946 onward, and the response bundles editorial facts with the price and an order link. It does not discuss failure behaviour for invalid or future dates, which the schema partially covers.

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 one dense, front-loaded block that opens with what the tool is and follows with the content list and triggers; it has no filler. It is a little long for single-parameter tool, but every clause carries information.

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?

There is no output schema, and the description compensates by enumerating what the preview contains, including price and order link, so an agent knows what to expect. With only one fully documented parameter, this is close to complete. Only the relationship to the 'preise' sibling remains unexplained.

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% and the single 'datum' parameter is fully documented in the schema, including the accepted formats and the year rules. The description only echoes the 'ab 1946' bound, adding no format or parsing guidance of its own. Baseline 3 is appropriate.

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 gives a specific verb and resource: it retrieves what happened on a particular day for a birthday-newspaper preview, and it lists the content types returned (headlines, number-one hit, birthday twins, calendar page, price, order link). This is much stronger than a tautology. The only gap is that it never names the sibling tool 'preise', even though it advertises that the price and order link are included, which leaves some overlap unresolved.

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 closing sentence gives explicit triggers: use it when someone asks what happened on their birthday or another date, or when someone is looking for a birthday gift. That clearly covers the intended context. It does not state when NOT to use it, i.e. how it relates to 'preise' for pure pricing questions, so it falls short of a 5.

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