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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety bar is low. Beyond that the description adds genuinely useful behavioral context: source-scoping, the rule that collection timestamps never backdate publication dates, and the warning not to sum overlapping sources or cumulative benchmarks. It omits auth, rate limits and pagination behavior, which keeps it short of a 5.

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?

Three dense sentences with the return shape front-loaded, followed by the two interpretive constraints. No filler sentences and no repetition of title or annotations; every clause carries a distinct rule the caller needs.

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 14-parameter, zero-required, no-output-schema tool this is under-specified: the response fields are only loosely gestured at ('observed MW and project counts') and pagination via limit/offset is never mentioned. The description conveys the domain and two caveats but leaves an agent guessing about most of the call surface.

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 0% across 14 parameters, so the description carries the full burden and largely fails. It hints at only a fraction of them - region, fuel, status (named directly), sourceId ('source-scoped') and the historical flag ('current collection history or historical benchmark series') - while to, from, kind, limit, offset, search, symbol, country and loadClass are entirely undocumented anywhere.

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 resource and scope: 'source-scoped observed MW and project counts by region, fuel and status', which tells an agent it returns power snapshot metrics with defined dimensions. It is clearer than a tautology, but it never names or contrasts itself against the close siblings (power.board, power.summary, power.coverage), so sibling differentiation is left to inference.

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?

Two usage caveats are given: 'never sum overlapping sources or cumulative historical benchmarks' and the instruction to treat current collection history and historical benchmark series separately. These imply when/how to use the output, but there is no explicit 'use this when X, use power.summary instead' routing against the many sibling power and market tools.

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