power_compare_periods

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

With no annotations provided, the description carries the full behavioral burden. It never states that this is a read-only analysis (no side effects), what defines a 'cycle', or how missing previous-cycle data is handled — all things an agent would want before calling a comparison tool.

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?

A single, front-loaded sentence with zero filler. The comparison scope is stated in the first few words, so the agent's decision is immediate.

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?

An output schema exists so return values needn't be explained, and the zero-param signature keeps the surface small. Still, with no annotations and no mention of what constitutes a cycle or whether the comparison is read-only, the description leaves a few gaps for an analysis tool.

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?

The tool takes zero parameters, so there is nothing for the description to explain beyond what the schema already conveys. Baseline 4 applies; the description adds no param detail because none is needed.

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 pairs the verb 'compare' with a well-defined resource ('current-cycle energy' vs 'equivalent previous-cycle period'), so an agent immediately knows this is a period-over-period delta tool. It stops short of naming why it differs from near neighbors like power_explain_usage_change, which also touches usage changes.

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?

There is no statement of when to reach for this tool versus power_explain_usage_change, power_forecast_bill, or power_estimate_load_impact. No prerequisites or exclusions are given; the agent must infer usage from the name and sibling list alone.

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