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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description's added value is its content disclosure: the result is only the title and first paragraph, with the full text behind a linked page and a free account. That is exactly the kind of expectation-setting an agent cannot get from the annotations.

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 short sentences with no filler; the payload scope is stated first and the truncation caveat second. Every clause earns its place.

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, so the description must describe return content, and it does: title plus first paragraph, with a pointer to where the rest lives. For a single-parameter read tool this is essentially sufficient, missing only explicit sibling routing.

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 enum already carries Dutch-to-English sign translation guidance, so the description adds no parameter detail. Baseline 3 applies since the schema does all the work.

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 resource and period: 'de maandhoroscoop van deze maand voor een sterrenbeeld'. This clearly separates it from daghoroscoop, weekhoroscoop and jaarhoroscoop by period, though it never names those siblings explicitly.

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?

Usable scope is implied by the period word 'maand', so an agent can infer it should pick this over the daily or yearly variant. There is no explicit statement of when to use it, when not to, or any pointer to the alternatives.

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