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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false and a closed world, so the safety profile is covered and the description adds little there. It does state the shape of the result (SDLT due plus effective rate) and cross-links to list_bundles, but omits behaviourally important detail for a tax tool, such as which tax-year/rate bands apply.

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?

Front-loaded with the verb and resource, then inputs, then output, then a cross-reference — a sensible order with no filler sentences. "Use for UK home buyers" is slightly redundant with the tool name but still earns its place as scope.

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 the description need not explain return values, and annotations cover the safety profile. Still, the phantom second-home parameter creates a gap between what the description promises and what the tool accepts, and the absence of any tax-year/rate context is a real omission for an SDLT calculator.

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?

The schema already documents both real parameters at 100% coverage, so the baseline would be 3. However, the description claims a "second-home flag" input that does not exist in the schema (which only accepts price and first_time_buyer, with additionalProperties=false), actively misleading an agent about the interface.

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 (compute UK Stamp Duty Land Tax) and scopes it to UK home buyers, which distinguishes it from the many generic finance/percentage calculators. It does not, however, distinguish itself from the closer sibling calculate_property_transfer_tax, which an agent might reasonably confuse it with.

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?

"Use for UK home buyers" gives a domain hint, and the pointer to list_bundles/`finance-uk` suggests where related tools live. There is no when-not guidance and no explicit alternative named (e.g., when to use this vs. calculate_property_transfer_tax or calculate_uk_council_tax), so routing is only implied.

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