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

Annotations already cover the read-only/idempotent/non-destructive profile, and the description adds genuine calculation semantics: 25% headroom on the continuous rating, the 2-3x motor surge assumption, and the two returned values. It stops short of saying how the surge is combined with headroom or whether standard inverter sizes are snapped to.

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?

Three tight sentences: what it computes, what it accounts for, and what it returns. Every sentence carries information and the purpose is front-loaded.

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 no output schema, the description does name the returned values (recommended wattage, DC current draw) and the safety profile is covered by annotations. Minor residual gaps are the treatment of surge-plus-headroom interaction and whether discrete standard sizes are suggested.

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 adds interpretive domain meaning to the inputs, clarifying that continuous power and startup surge are treated differently and that systemVoltage drives the DC current result. That meaning is not in the schema field descriptions.

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 uses a specific verb (calculate) and resource (recommended inverter size) and scopes it to AC loads fed from a DC battery system. That subject matter alone separates it cleanly from siblings like calculate_battery_bank or calculate_solar_size.

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?

Usage is implied by the AC-load-to-DC-system framing, but the description never states when to choose this over calculate_power_budget or calculate_charging_time, nor any prerequisites. It is adequate context without explicit routing guidance.

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