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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds real behavioral context by pinning the rate year, the £225,000 nil band, and the absence of first-time buyer relief. It does not describe the shape of the result (e.g. whether a band breakdown or a single total is returned), which is the main remaining gap.

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?

One sentence, front-loaded with the jurisdiction and tax name, with the key rate facts packed into a parenthetical. No wasted clauses and nothing an agent must scan past to find the subject.

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 two-parameter read-only calculator with full schema coverage and no output schema, the description supplies the tax regime details an agent needs to trust the result. It is only slightly incomplete in not stating what the response contains, though 'band by band' hints at a per-band breakdown.

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%, so the baseline is 3, but the description goes beyond the schema by explaining that the nil band is £225,000 'for everyone' and that 'additional' means the higher rates for additional properties rather than merely an opaque enum label. That meaningfully disambiguates the buyerType parameter.

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 the exact tax (Wales Land Transaction Tax), the rate year (2026/27), and the computation basis (band by band), which clearly separates it from siblings like scotland_lbtt and uk_stamp_duty_england_ni. It stops short of an explicit verb such as 'calculate', leaving the agent to infer that from the name and context.

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?

Jurisdiction is stated, so an agent can infer this is the tool for Welsh property purchases rather than the England/NI or Scotland equivalents, but there is no explicit when-to-use or when-not-to-use sentence naming those alternatives. The buyerType distinction is implied by 'additional properties' but not framed as guidance.

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