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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, closed-world, so the safety profile is covered. The description adds value by disclosing the shape of the result (low/high range, regional context, contractor comparison guidance), which is meaningful because there is no output schema to convey this.

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 filler, and the usage trigger is front-loaded before the behavior and output summary. Every sentence earns its place.

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, the description adequately signals what comes back (cost range, regional context, contractor guidance) and the schema fully documents inputs. Only a thin gap remains on precision of the returned values and any caveats, which is minor for a deterministic read-only 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?

Schema description coverage is 100% with enum values for system, work_type, and efficiency, so the schema already carries the parameter meaning. The description mentions home size, system type, and efficiency but omits work_type and adds no syntax or format detail beyond the schema, fitting the baseline 3.

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 states a specific verb and resource ('returns low/high cost range' for HVAC work) and names the trigger question directly, so an agent can identify it as a cost estimator. It does not explicitly distinguish itself from the many sibling cost calculators (electrical, plumbing, roofing), relying on the tool name for that differentiation.

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?

It gives a clear use condition ('Use when a user asks what HVAC replacement, installation, or repair will cost'), which is actionable context. However, it offers no exclusions or routing away from the sibling calculators when the user's question is not HVAC-specific.

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