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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds exactly the context the rubric rewards: 'Free, no authentication required. Rate limited.' It also discloses the substantive zero-rating rule the calculation applies, so the agent knows the behavioral bounds of the estimate.

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?

Four telegraphic sentences, front-loaded with the core purpose before the caveats and operational notes. Dense and mostly waste-free, though the clipped phrasing ('FIRST supply', 'Rate limited') assumes some domain familiarity.

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?

An output schema exists, so return values need not be described. The description covers scope, exclusions, the key domain rule, and operational constraints (free, no auth, rate limited), leaving only minor parameter documentation gaps against a 0%-coverage schema.

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 0% across 5 parameters, so the description carries the full documentation burden. It explains the semantics behind firstSupply and yearsSinceCompletion ('zero-rating requires FIRST supply within three years of completion') and the propertyType split, but says nothing about amount or the includeVat toggle and its default.

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?

Specific verb (Estimate) plus resource (VAT on ordinary commercial/residential property in AED), with an explicit boundary against transfer fees and against sibling uae_vat's broader scope. The exclusion of mixed-use/specialist properties further sharpens what this tool does and does not cover.

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?

Gives clear when-to-use conditions (ordinary commercial or residential property) and when-not conditions (transfer fees, mixed-use, specialist properties). It stops short of naming the sibling tool to use instead (e.g. uae_vat) for the excluded cases, which keeps it from a 5.

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