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

Annotations declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds real value beyond that by disclosing the precision profile — transfer duty is exact while conveyancing, Deeds Office and bond registration are estimates quoted from the LSSA guideline. It does not say anything about the return shape or rounding, but the accuracy caveat is the materially important disclosure here.

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?

Two sentences, zero waste, and the exact-vs-estimated distinction is front-loaded right after the scope statement. Nothing extraneous.

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 read-only calculator with no output schema, the description should explain what comes back at a high level and what each input does. It covers the accuracy caveat well but leaves the VAT-vendor flag and purchase_price semantics undocumented, which is a real gap for a costing tool.

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 only 33%, so the description is expected to compensate. It does not: purchase_price has no description at all in either place, and seller_is_vat_vendor is completely unexplained — an agent cannot tell how this boolean changes the estimate (e.g. whether transfer duty is replaced by VAT). Only bond_amount is indirectly hinted at via 'bond registration costs'.

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 — estimates once-off property purchase costs in South Africa — and enumerates the components (transfer duty, conveyancing, Deeds Office, bond registration). This scope is clearly distinct from the sibling tools transfer_duty (one component) and bond_repayment (ongoing costs), so an agent can route without opening a 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?

Use is implied by the scope statement: call it for a total once-off cost picture rather than a single fee. However, it never explicitly says when to prefer this over the transfer_duty sibling or when to use transfer_duty alone, and no prerequisites or exclusions are given.

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