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

Annotations already cover read-only safety, but the description adds genuinely non-schema behavior: per-call pricing via x402 on Base/Solana/Arc and the fact that failed calls are not charged. It does not describe latency or freshness guarantees beyond 'latest report day', which is a minor 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?

Front-loaded with what data is returned, then scope, then filter, then cost — a sensible ordering with minimal waste. The pricing sentence is dense but earns its place for a paid tool; overall length is slightly long for a single-parameter lookup.

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 need no explanation, and the description covers source, scope, filter, and cost. What remains thin is the time dimension (whether 'latest report day' means business days and what happens on weekends/holidays), which matters for a daily report 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?

Schema coverage is 100% and the schema already says 'Optional: part of a unit name, e.g. Vogtle or Diablo'. The description's 'Filter by part of the unit name' restates that substring-match semantics without adding new information, so the baseline 3 applies.

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 resource (NRC daily Power Reactor Status Report), specific content (each unit's % of rated power on latest and prior day, plus counts of full-power/reduced/offline units), and explicitly excludes worldwide IAEA PRIS data. That distinguishes it from nearby siblings like energy_uranium_u3o8_yellowcake and energy_us_electric_grid_monitor.

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 a clear scope boundary ('US units only, about 94; worldwide IAEA PRIS data not included') that tells the agent when this tool will not satisfy a request, and explains the one filter. It does not name an alternative tool for the excluded worldwide case, so it stops short of full routing guidance.

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