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

Adds real context beyond the annotations: the response is deliberately truncated to the title and first paragraph, and the rest lives on a linked page behind a free account. That sets correct expectations for output completeness and implicitly tells the agent this tool will not fetch the full article. Consistent with readOnlyHint, idempotentHint and openWorldHint=false, since no external retrieval is performed.

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?

One sentence, front-loaded with what is returned, followed by the crucial caveat about the truncated text. Nothing is repeated or wasted.

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 one-parameter read tool with full annotation coverage and no output schema, the description covers scope, return shape and the truncation limitation. It could still say what happens when no horoscope exists for the week or confirm the output language, but nothing essential to correct invocation 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% and the single enum parameter already documents the twelve Dutch sign names plus translation mappings. The description adds only the generic phrase 'voor een sterrenbeeld', so the schema is doing essentially all the work. Baseline 3 applies.

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?

States a specific verb+resource pair ('de weekhoroscoop van deze week voor een sterrenbeeld') and names the returned fields (titel en eerste alinea). The 'deze week' scope implicitly separates it from daghoroscoop/maandhoroscoop/jaarhoroscoop, but it never names those siblings or the condition that selects them.

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?

Usage is only implied: you call it when you want the current weekly horoscope for one sign. There is no explicit when-not, no mention of the daily/monthly/yearly siblings, and no note on what to do if the agent needs the full text instead of the excerpt.

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