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

With no annotations, the description carries the full behavioral burden and does so well: it discloses the free window (latest month / most recent 30 days), that a Pro key unlocks full history, the licensing terms, and a data-integrity guarantee ('flagged, never filled', exact as published with source URL). This is genuine context beyond a bare read-only claim; a brief note on pagination/rate limits would round it out.

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?

Information-dense and front-loaded with the core purpose, but the free-tier rule is stated twice ('the free window is the latest month' and 'the most recent 30 days of each series'), and the licensing sentence is a full trailing block. Slightly redundant rather than wasteful, but not tight.

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?

No output schema exists, so the description correctly explains return content (unit, date, original source URL, incomplete-day flags). Combined with 86% schema coverage and the free/Pro access model, an agent has nearly everything needed to call it correctly; only pagination edge behavior is unaddressed.

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 already 86%, so the baseline is 3. The description adds value by restating the default state/sector selections and tying the start parameter's historical reach to the free-vs-Pro key boundary, which clarifies a constraint the schema only partially encodes ('Older dates need a Pro key').

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 verb+resource: U.S. retail electricity statistics by state from the EIA, enumerating the four measure families (price, sales, revenue, customers) and sector breakdown. It also names the sibling tool (electricity_data_product with slug 'us-electricity-prices') for the ranked-table alternative, so an agent can distinguish it from other electricity_* siblings.

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?

Explicit defaults (Texas + U.S. residential price) and a clear routing rule to electricity_data_product for a ranked all-states table. It also surfaces the free/Pro boundary condition. It stops short of distinguishing itself from trend-oriented siblings like electricity_price_trends, so it is clear context but not exhaustive when/when-not guidance.

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