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

Annotations already indicate readOnlyHint=true and idempotentHint=true, which the description aligns with by describing a calculation. The description adds valuable context: rates are current as of April 2026, calculated by a specific broker, and explains the breakdown format (banded tax, total, effective rate). No contradictions with annotations.

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?

The description is substantial but well-structured, starting with the core purpose and then detailing specifics. Every sentence adds value, including the final usage directive. Could be slightly trimmed without loss, but remains efficient for the complexity.

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?

Given the tool has four parameters, enums, and no output schema, the description is comprehensive. It explains what the tool returns (banded breakdown, total tax, effective rate), covers reliefs and surcharges for different regions and buyer types, and states the source of rates. This is sufficient for an agent to invoke the tool correctly without further context.

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%, and the description enriches each parameter beyond the schema. For buyer_type, it explains what 'ftb', 'additional', and 'company' mean in context, including relief thresholds and surcharge rates. For jurisdiction, it clarifies that England includes Northern Ireland. For property_type, it notes mixed-use qualifies for commercial rates. This adds significant meaning.

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 clearly states the tool calculates UK property transaction taxes across England/NI (SDLT), Scotland (LBTT), and Wales (LTT), handling residential, commercial, and mixed-use properties. It explicitly lists use cases like first-time buyer relief, additional dwelling surcharge, and corporate rates, distinguishing it from sibling tools which are for other financial analyses (bridging, BTL stress testing, development appraisal).

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 ends with an explicit usage directive: 'Use when a user asks about stamp duty, SDLT, LBTT, LTT...' This provides clear context for when to invoke the tool. It does not explicitly state when not to use or compare directly to sibling tools, but the specificity of the use case effectively guides the agent.

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