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

Annotations already declare readOnlyHint=true, so the description adds value by detailing what the returned score includes, the fields returned, and the update cadence 'Updates: on source cadence.' This goes beyond the annotation without contradiction. However, it does not specify the exact source cadence or any limitations, so there is a small gap in behavioral disclosure.

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?

The description is concise and well-structured: first sentence states what it does and the output, second gives use cases, third gives update frequency. Every sentence earns its place with no redundancy or fluff. It is front-loaded with the core purpose.

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?

The description covers the core functionality, scope (all US counties), output fields, use cases, and update cadence. There is no output schema, but the description lists the return fields, which suffices. The optional 'days' parameter is not mentioned in the description itself, but it is fully documented in the schema, so the gap is minor. Overall, the description is nearly complete for a read-only data retrieval 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?

The input schema has one parameter 'days' with a full description covering the daily history series and Gold tier requirement, giving 100% schema coverage. The description text itself does not mention this parameter or add any additional meaning beyond the schema, so the baseline of 3 is appropriate. Since the schema thoroughly explains it, no further compensation is needed.

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 clearly states the tool returns a 0-100 per-county EV-charging build-out score for all 3,222 US counties, specifying the metrics and normalized per capita. This is specific and distinguishes it from sibling tools, which are likely unrelated data sources. The verb 'Returns' and explicit resource make the purpose unambiguous.

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 description explicitly states when to call the tool: 'when the user asks about local EV-charging build-out, charging deserts, or county EV readiness, or when timing charger deployment, fleet electrification, or site-selection decisions.' It provides clear context but does not mention when not to use it or alternatives, which would merit a 5. Given the lack of direct sibling tools for EV charging, this is acceptable.

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