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

Annotations already declare it read-only, non-destructive and closed-world, and the description adds substantial behavior beyond that: the CSolar price table with its date (setembro/2026), the Sorocaba/SP irradiation basis, the geographic validity caveat, the estimate-not-quote disclaimer, and an explicit statement that no personal data is requested or stored.

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?

Front-loads the purpose, then the outputs, then the geographic caveat and disclaimers, with no filler sentences. The enumeration of return values is mildly redundant given an output schema exists, which keeps it from a perfect score, but every sentence still 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 an output schema present, the description does not need to detail return fields yet still summarizes them, and it supplies the pricing basis, geographic scope, disclaimer and privacy note an agent needs to call and interpret this correctly. Nothing material is missing for a zero-required-parameter estimation 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 100%, so the schema already documents all four parameters, including the 'use when you don't know kWh' note for valor_conta_mes and the 'does not change the calculation' note for cidade. The description adds only a high-level restatement of the two input modes, which is the expected baseline when the schema does the heavy lifting.

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 a microinverter solar system) and enumerates exactly what it returns (kWp, module count, generation, savings, installed price, payback). It is very clear, but it never names or explicitly differentiates from its sibling check_service_area, which covers the same 'served area' concern the description raises.

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 clear usage context: accepts either monthly kWh consumption or the monthly bill value, is an estimate rather than a quote, and outside São Paulo the numbers are reference only. It stops short of an explicit alternative (e.g. 'to verify coverage, use check_service_area') or an exclusion on required inputs, so it is good but not complete.

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