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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds that the calculation is jurisdiction-dependent and conditionally applies three surcharge/relief regimes, which is useful context, but it says nothing about computation assumptions, defaults applied silently, or what the result contains.

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 dense sentence that front-loads the core action and then qualifies scope by nation and relief type. No filler, though the long tail of surcharge clauses makes it slightly heavy for one sentence.

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?

With 9 parameters, no output schema, and a sibling set crowded with similar calculators, the description covers scope well but says nothing about the returned value (a tax figure, a band breakdown?) or the defaults silently applied to country, completionDate and propertyUse. Adequate but with clear gaps for a calculator whose output is its whole point.

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 67%, and the description meaningfully fills some of the gap: it ties first-time buyer relief to firstTimeBuyer, the additional property surcharge to the other-property/replacement flags, the non-resident surcharge to ukResident, and region choice to the country enum. It leaves company, propertyUse and completionDate unexplained, so it does not fully compensate.

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?

States a specific verb and resource (calculate stamp duty / tax on buying property) and enumerates exactly what falls in scope: SDLT, LBTT, LTT, band-based computation, first-time buyer relief, additional property and non-resident surcharges. This distinguishes it cleanly from siblings like calculate_capital_gains_tax or calculate_vat.

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?

The description implies when the tool is applicable (property purchases, with conditional reliefs) but never states when to use this versus the many other tax calculators, nor any exclusions or prerequisites. Usage is inferable from purpose but not explicitly guided.

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