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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds meaningful context beyond that: the price is 'settled' (not forecast), quoted in micro units of local currency, and the response carries a USD conversion, demand figure, and negative-price flag — useful disclosure given there is no output schema.

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 sentence with the core purpose front-loaded and the return-field details packed into a trailing parenthetical; no wasted words. The compression is slightly terse, but 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?

For a two-parameter read tool with full schema coverage, the description covers the main gap left by the absent output schema by enumerating the returned fields. It omits any mention of the settlement timestamp/interval or staleness, which is the only notable remaining gap.

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%, and the market enum values plus the region example and the pointer to grid_regions are fully documented in the schema. The description adds nothing about parameter meaning, so it sits at the baseline of 3.

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 gives a specific resource and a qualifying scope: 'Latest settled wholesale electricity price for a region,' with 'latest settled' distinguishing it from forecast or historical variants. It does not name the sibling tools (grid_price_history, grid_day_ahead) it is disambiguated against, so it falls short of a 5.

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 word 'settled' implicitly signals this is for actual cleared prices rather than day-ahead forecasts, which hints at when to pick it over grid_day_ahead or grid_price_history. However, there is no explicit when-to-use or when-not-to-use statement and no alternative is named.

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