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

Annotations already declare readOnlyHint=true, covering the safety profile. The description adds that the returned meterApiName values feed other usage tools, which is useful workflow context, but says nothing about pagination, result size, or auth requirements. Adds some value beyond annotations, hence a middle score.

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?

Two compact sentences lead with the scope and returned fields, followed by the downstream use case. The trailing 'API: GET /meters' is mildly redundant but conventional and costs little.

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?

With no output schema, the description usefully names the returned fields and their downstream purpose, which is what an agent needs to consume the result. Missing details like pagination or total count keep it from being fully complete.

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 tool takes zero parameters, so there is no parameter semantics to mis-explain; baseline 4 applies. The description instead documents the response fields, which the schema does not cover since there is no output schema.

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 and resource ('List all meter definitions in your account') and enumerates the fields returned (id, meterApiName, label, meterType, aggregation). The scope is unambiguous and clearly distinct from the usage-oriented 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?

Explains the downstream purpose — 'Use meterApiName values here as inputs to usage tools' — which tells the agent why and when to call this before usage tools. It stops short of naming a specific alternative tool or stating exclusions, so it is clear context rather than full routing guidance.

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