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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful context by stating the values are derived from the live generation mix, implying freshness, but it does not disclose behavior around time ranges or response limitations.

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 a single efficient sentence that front-loads the key output metrics and their units/scale. It contains no filler, though it does sacrifice important parameter context for brevity.

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?

Given no output schema and zero parameter documentation, this description is incomplete. It does not explain what zone values are expected or how optional from/to affect the result, so an agent is left without enough context to invoke the tool reliably.

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%, and the description provides no meaning for the three parameters (zone, from, to) beyond their names. The units and green score range describe the output, not the inputs, leaving the required zone parameter completely unexplained.

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 identifies the resource: carbon intensity in gCO2eq/kWh and a green score on a 0-100 scale. It distinguishes itself from price- and renewables-focused siblings by describing the output as derived from the live generation mix, though it lacks an explicit verb.

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?

No guidance is provided about when to use this tool versus siblings such as get_forecast or get_renewables. The description gives no context on selecting zones, time ranges, or alternatives, so an agent must infer usage entirely from the name and schema.

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