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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is carried by structured data. The description adds value by disclosing the return contents (cost, payback timeline, incentives), which is meaningful since no output schema exists; it does not, however, mention that results are estimates or what assumptions underlie them.

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 sentences with the usage trigger front-loaded and the return values immediately after. No filler or redundant restatement of the title.

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 full schema coverage and annotations, the description supplies both the trigger and a preview of outputs. The only material omission is any caveat about estimate assumptions or regional incentive applicability.

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 clear enums for battery, shading, and roof_type, and a bounded numeric monthly_bill, so the schema does the heavy lifting. The description adds no extra parameter meaning (e.g., how shading or battery choices affect the estimate), which is the expected baseline when coverage is complete.

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+resource ('solar installation cost' calculation) and its output scope (system cost, payback timeline, incentive guidance). An agent can distinguish it from the roofing/hvac/electrical cost calculators because the resource domain is named explicitly.

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?

Gives a clear trigger condition: use when the user asks about solar panel cost, installation cost, or payback period. However, it offers no exclusions or routing guidance relative to its siblings (e.g., when solar vs. electrical cost estimation is appropriate), leaving a small gap.

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