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

Annotations already declare readOnlyHint/idempotent/non-destructive, so the safety profile is covered. The description adds nothing behavioral beyond that ('Returns ROI years and lifetime savings' merely restates what the output schema already provides), and it discloses no assumptions such as discount rate or lifetime horizon.

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-loaded with the core purpose, then inputs, outputs and a cross-reference in four tight sentences. The input enumeration is wasted space because the schema covers it and does so inaccurately.

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 and full annotation coverage, the description needn't explain returns or safety, and it correctly routes to list_bundles. But the inaccurate input list and the absence of any lifetime/discount assumptions leave the agent with a slightly wrong model of what to supply.

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%, so the baseline is 3, but the description's input list is misleading: it names 'kW capacity' and 'location production', which are not parameters at all, while the actual inputs are system_cost, annual_kwh and price_kwh. The mismatch adds confusion rather than meaning beyond the schema.

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?

Specific verb+resource: 'Compute solar panel return on investment over their lifetime', with scope (lifetime) stated. It does not differentiate from close siblings like calculate_roi or calculate_solar_panel_output, but the purpose itself is unambiguous.

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?

'Use for energy audit' gives an implied context, and it points to list_bundles for related 'energie' calculators. However, it never says when to prefer this over calculate_roi or calculate_solar_panel_output, so routing remains guesswork.

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