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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuine context by disclosing the rate basis (rand-per-m² in South Africa) and that fees are applied as optional percentages, but it says nothing about accuracy, assumptions, 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?

Two tight, front-loaded sentences with no filler, and the core inputs are stated before the optional add-ons. Slight deduction because the second sentence describes a 'municipal plan fees' option that does not correspond to any actual parameter.

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 no output schema and 7 parameters at 14% description coverage, the definition leaves real gaps: three parameters (contingency_pct, include_vat, double_storey) are unexplained and the return shape is never hinted at. The geographic and rate-basis context is helpful but not enough to fully cover the tool's complexity.

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 only 14%, so the description must compensate and it does so partially: it explains floor area, quality level, region, and percentage-based fees. It omits contingency_pct, include_vat, and double_storey entirely, and oddly references 'municipal plan fees' which is not a parameter in the schema.

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 a specific verb (estimates), resource (construction cost of a new house or extension), and even the method (rand-per-m² rates) and geography (South Africa). The 'new house or extension' scoping implicitly separates it from roof_replacement_estimate and renovation_flip_check, though it never names those siblings.

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?

There is no explicit statement of when to use this tool versus the sibling estimators, nor any prerequisites or exclusions. An agent must infer from the resource scope alone that this is for greenfield builds rather than renovations or roof work.

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