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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description adds one genuine behavioral detail annotations cannot convey: results include incomplete states and mix paid measurements with free checks. It says nothing about ordering, pagination, or result size.

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 efficient sentence with the scope statement front-loaded. The 'Use this to' preamble is mildly redundant but 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?

For a zero-param, read-only list tool with rich annotations and no output schema, the description conveys what the returned set contains (paid measurements, free checks, incomplete states), which is the essential missing piece. Ordering, pagination, and volume remain undocumented, leaving the return behavior partially opaque.

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?

Zero parameters, so there is no parameter semantics burden on the description; baseline is 4. The description correctly describes what the call operates over rather than inventing parameters.

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 clear verb ('list') and resource ('your paid measurements and free checks'), which maps to the runs/measurements domain despite the name/description wording mismatch (runs vs. measurements). It does not distinguish itself from siblings like compare_runs or list_alerts, so an agent gets no sibling routing signal.

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?

'Use this to list...' implies the usage context but offers no when-not conditions and names no alternative. With sibling tools such as compare_runs and list_alerts present, the agent is left to infer that this is the unfiltered enumeration entry point.

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