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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-obvious behavioral semantics beyond that: only the single highest starting surge is counted (motors rarely start simultaneously), and margin is an optional user-chosen buffer. It does not state whether margin applies to running watts, starting watts, or both, which is a real gap.

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 front-loaded with the goal, then the formula, then supporting details, and each sentence carries information. The amps-at-240V note is mildly tangential for a generator-sizing tool, keeping it from a 5, but nothing is padded.

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?

There are 18 optional parameters, no output schema, and no annotations describing results, yet the description never states what the tool returns (total running watts, total starting watts, amps) or how margin is applied. The calculation method is well covered, but the return contract and margin semantics are left for the agent to infer.

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 every per-item wattage, starting-surge value, and default is already documented in the schema. The description's param-related statements ('margin is an optional buffer you choose', 'largest other motor') largely restate the schema text, so the baseline of 3 is appropriate.

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 ('What size generator you need for a power outage') and immediately defines the two outputs (running watts and starting watts), which cleanly separates it from siblings like calc_voltage_drop or calc_appliance_energy_cost. An agent can tell what this computes without opening the schema.

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: 'add the running watts of everything you will run at once, then add the single biggest motor starting surge' and 'Enter how many of each item you plan to run at the same time.' It does not name a when-not or an alternative sibling tool, so it stops short of a 5.

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