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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so safety is covered. Beyond that the description adds genuinely useful context an agent could not infer: the free daily allowance and the $0.001 USDC per-call x402 charge, plus the temporal windows returned. It stops short of noting freshness lag or update cadence hedging.

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 filler, with the core scope front-loaded and the pricing caveat placed last where it belongs. Every clause carries information.

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?

With an output schema present, return-value detail is not the description's job; annotations carry the safety profile; there are no parameters to document. What remains for the description — scope, time grain, units, and cost — is all present and correct.

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 disambiguate; the baseline for a parameterless tool applies. The description's unit and time-window notes are output semantics, not input semantics, so no credit or penalty is warranted here.

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 (current GB generation by fuel type) with concrete units (MW and %) and a time grain (latest 5-minute reading). It implicitly separates itself from siblings like generation-today and generation-history via 'current' and the 5-minute cadence, but never names or contrasts those siblings explicitly, and the trailing 'last half hour / 24 hours' is ambiguous about what exactly is returned over those windows.

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 guidance on when to choose this tool over generation-today, generation-history, or generation-today-adjacent siblings. The only conditional language concerns billing ('free within the daily allowance, then $0.001 USDC per call'), which is cost context rather than usage guidance.

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