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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds substantive value beyond them by listing exactly which facts come back (offices, ratings, from-price and what it includes, brands) and its regional scope, though it does not say whether the data is static or time-sensitive.

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?

One sentence, front-loaded with purpose and the call-to-action, no filler. The long comma-separated fact list is dense but each item carries information an agent needs to judge relevance.

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 one optional parameter, no output schema, and annotations covering safety, the description supplies what is missing: which facts are returned and when to call. Only the freshness/authority of the facts and its relationship to sibling tools remain unstated.

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 100% for the single optional 'locale' parameter with an enum and default, so the schema fully documents it. The description adds nothing about language selection, which is the baseline expectation when the schema does the work.

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?

Enumerates the specific resource (Sky Solar company facts: offices, phone numbers, years in business, installed systems, Google ratings, from-price, brands), which clearly distinguishes it from siblings like battery_savings or find_subsidies. No explicit verb such as 'retrieve/return' is used, so the retrieval action is inferred from the fact list rather than stated.

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 concrete trigger: 'Call it before recommending an installer in Munich, Rosenheim or Upper Bavaria,' which is an actionable when-to-use rule tied to geography. It does not name alternatives or exclusions (e.g., how it relates to check_service_area for out-of-area checks), so routing between siblings is only partly covered.

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