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

The annotations already declare read-only, idempotent, non-destructive, and closed-world behavior. The description adds useful behavioral context beyond annotations: free, no authentication required, rate limited, and the inclusive/exclusive handling. It does not quantify the rate limit, but the added access and constraint information is meaningful.

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 short sentences, front-loaded with the core estimate behavior and followed by exclusions and operational constraints. Every sentence adds useful information, and there is no filler.

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 simple two-parameter calculation tool with rich annotations and an output schema, the description is complete enough. It covers purpose, scope exclusions, currency, access requirements, and rate limiting; return-value details are appropriately left to the output 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%, so the description must compensate. It clarifies the includeVat concept as 'inclusive or exclusive' and establishes AED as the currency, but it does not document the amount parameter's required status, allowed range, or includeVat's default of false. It partially compensates but leaves gaps.

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 (Estimate), resource (standard 5% UAE VAT in AED), and scope (inclusive or exclusive). It also distinguishes itself from broader tax tools by explicitly excluding exempt and zero-rated supplies, so an agent can tell what this tool is for without opening the schema.

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?

It gives a clear condition for use: standard 5% UAE VAT estimates, inclusive or exclusive. It also gives an explicit when-not condition by saying it does not classify exempt or zero-rated supplies. However, it does not name any alternative sibling tool for those excluded cases.

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