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

With no annotations provided, the description carries the behavioral disclosure burden. It does disclose one useful trait: missing inputs fall back to documented defaults. It does not explicitly state that this is a pure read-only calculation or what it returns, though the calculator nature makes that reasonably evident from the name.

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?

The description is a single short sentence with the main action front-loaded. But the typo 'calculator calculator' and the misleading input enumeration are waste, and the list does not earn its place because it conflicts with the schema.

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?

Given six parameters, no output schema, and no annotations, the description should at least clarify what the calculator computes, what the expected output is, and how it relates to calculator_describe. None of that is present, and the mismatched input list increases confusion rather than reducing it.

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?

The schema covers all six parameters with descriptions and defaults (100% coverage), which normally establishes a baseline of 3. The description actively detracts, however, by listing inputs ('Electricity you buy each year', 'System size that covers it') that do not correspond to the schema's ppw, bill, rate, orient, battery, and battCost, potentially misleading an agent about what to pass.

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 names a specific action ('Run...') and resource ('California solar cost calculator'), so an agent can roughly tell what it does. However, the redundant 'calculator calculator' phrasing and an input list (kWh, kW, panels) that does not match the actual schema (ppw, bill, rate, orient, battery, battCost) muddle the statement. It also does not differentiate this from the sibling calculator_describe.

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?

No guidance is given on when to use this tool versus the siblings (calculator_describe, submit_enquiry, etc.). The only usage hint is that missing inputs fall back to their documented defaults, which is useful but does not address alternative selection or prerequisites.

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