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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuine context beyond that: the tool is a counting/estimation pass that does not perform structural design and returns no pricing, and it details what the response body contains. It does not discuss limits or error behavior, but there is little else to disclose for a deterministic computation.

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, purpose front-loaded ahead of the output description and the two exclusions. The first sentence is dense with parentheticals but every clause carries information; nothing is redundant filler.

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 return values need not be described, yet the description still frames the result shape usefully. Annotations cover safety, and the description covers scope and functional limits. For an 11-parameter nested-object tool the coverage is solid, with only per-parameter unit/dimension behavior left largely to the schema.

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 64% across 11 params, so the schema does much of the work. The description contributes a conceptual map of the inputs ('footprint, walls, roof, openings'), which hints at the values, selection/roofSelection, and opening parameters, but it adds no per-parameter syntax or unit guidance beyond what the schema already provides.

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?

Specific verb (estimates) plus a tightly scoped resource: materials for one rectangular house, one or two storeys, from enumerated input groups (footprint, walls, roof, openings). It also states the output contents (quantities with what to order, assumptions, storey plans, labour hours). An agent can distinguish it from create_drawing ('does not design a structure') and from quoting tools ('No prices') without opening the 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?

Clear about what the tool is for and where its boundary lies, with two explicit exclusions that implicitly route the agent elsewhere: 'It counts; it does not design a structure. No prices.' No sibling is named directly, so the routing to create_drawing or check_quote is inferred rather than stated.

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