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

Annotations already declare readOnly, idempotent, and non-destructive behavior, and the description adds meaningful behavioral context: results are sorted by estimated cost, estimates are approximate and may differ from actual bills, and the service may receive affiliate compensation. It does not describe output shape or edge cases like empty green-only results, but the annotation coverage lowers the bar.

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 compact: one sentence states the function and sort order, a second gives the necessary accuracy caveat, and a third discloses the affiliate relationship. It is front-loaded and 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 moderately complex search tool with no output schema, it communicates the core contract: inputs, candidates returned, annual cost estimate, sorting, and caveats. It could be more explicit about result fields or empty-result behavior, but the rich parameter schema, annotations, and sibling context cover most of what an agent needs.

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 the schema already documents all six parameters thoroughly, including enums and area mappings. The description adds the relationship between household_size and monthly_kwh as alternative inputs, but this is mild added value; 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?

The description opens with a specific verb-resource pair: searching household electricity rate plans from area, contract amperage, household size, or monthly kWh, and adds the distinguishing output feature of annual cost estimates sorted by cheapest first. This makes it clearly distinct from sibling tools like search_gas_plans or search_mobile_plans even without an explicit sibling comparison.

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?

The description clearly states the relevant input dimensions and the output ordering, so an agent can infer this is the tool for residential electricity plan discovery with cost estimates. It does not explicitly name alternatives or state when not to use it, such as using compare_plans for detailed comparison, 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.