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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered; the description adds genuinely new context that the content is fixed and contains 'no amounts that change per year' (so no repeated calls are needed for updated figures), that output is bilingual Dutch/English, and that it links to the Belastingdienst. It does not describe the response shape, but the annotations carry the safety burden so a 4 is fair.

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, front-loaded with the purpose and the topic list, with the stability caveat in a compact clause. Almost no waste, though the phrase 'Fixed, factual explanation' is slightly redundant and the Belastingdienst link could be folded in more economically.

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 no-parameter, no-output-schema explainer, the description covers language, scope, contents, the authoritative source link and the static nature of the data. Minor gaps remain: it does not say anything about disclaimers or whether the answer is prose versus structured, but nothing essential to calling it 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?

There are zero parameters, which is the baseline case, and the description correctly signals the tool is callable without input. It adds no misleading parameter expectations.

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 verb and resource: a fixed factual explanation of how crypto is valued for Dutch box 3, and it enumerates the covered topics (reference moment, which price, own wallets, actual return). That distinguishes it from data-returning siblings like get_reference_price or value_portfolio, though it does not explicitly name an alternative.

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 implied rather than stated: the content list ('reference moment, which price to use, own wallets, actual return') tells an agent this is the rules-explainer for Dutch box 3 crypto questions. It never explicitly says when to call it instead of get_reference_price or value_portfolio, nor when not to.

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