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

With no annotations, the description carries the full disclosure burden, and it does substantive work: it names the 15,600 EUR rolling twelve-month threshold and, unusually, states that article 11(1) services from abroad and intra-community supplies carry no separate threshold, which is non-obvious behavioral nuance an agent could not guess. It still omits what the result looks like and any caveats about the decision being advisory.

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?

A single front-loaded sentence that opens with the decision to be made and then attaches only the specific statutory rules that modify that decision. It is dense but every clause carries information; a short break into purpose and rules would read better than the long trailing list.

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 are no annotations and no output schema, so the description must supply everything an agent needs to call and interpret the tool; it explains the decision logic well but never states the return shape (boolean versus decision plus reasoning) or the assumptions behind the supplied turnover figure. Adequate for invocation, incomplete for interpretation.

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 only 25% (just one of four parameters documented), so the description must compensate, and it partially does: the article 11(1) services clause and the intra-community-supplies clause explain how two of the undocumented booleans are treated, and the non-established-business clause maps to established_in_cyprus. However, it says nothing about the units or composition of taxable_supplies_last_12_months (EUR? VAT-inclusive? zero-rated/exempt inclusion), leaving the required parameter ambiguous.

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 states a specific verb and resource: deciding whether a business must register for Cyprus VAT, with the exact statutory threshold named. It is clear what the tool computes, but it never explicitly contrasts itself with adjacent siblings such as cyprus_tax_residency_test or cyprus_compliance_obligations, so an agent must infer the boundary from the subject matter alone.

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 agent can infer the tool applies when checking a Cyprus VAT registration obligation from the enumerated fact patterns. There is no explicit when-to-use, when-not-to-use, or named alternative for neighbouring questions (residency, other compliance obligations), so routing depends on inference.

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