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

With no annotations, the description carries the full burden, and it does add a genuinely useful licensing constraint (free for non-commercial use with attribution; commercial requires Pro). However, it says nothing about data freshness, the basis of the savings estimate, or pagination/return shape, so the behavioral picture is only partially filled in.

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?

Two sentences, zero waste, and the core action (compare my rate against cheapest plans, estimate savings) is front-loaded before the secondary licensing note. Every sentence earns its place.

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?

For a 4-parameter tool with no output schema, the description conveys the input concept and the headline result (yearly savings), and the schema documents utility and usage inputs well. What is missing is any sense of the returned comparison detail or how current the plan data is, which an agent would want before promising results.

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 75%, with the required current_cents_per_kwh left undocumented in the schema; the description usefully defines it as an all-in cents-per-kWh figure taken from the bill or EFL. That compensates for the gap and adds meaning beyond the schema, though it offers no guidance on the optional usage parameters.

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 states a specific verb (compare) and resources (household's current all-in rate vs. the cheapest plans in their utility) plus the output (yearly savings estimate). It is clearly distinguishable from bare listing tools like electricity_cheapest or electricity_rank_plans, though it never names the sibling it differs from.

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 only implied: the agent must infer that this tool applies when the user supplies their own rate from a bill or EFL and wants savings rather than a raw plan ranking. There is no explicit when-to-use/when-not guidance and no pointer to alternatives such as electricity_cheapest.

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