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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered. The description adds only that the result is service-wide rather than scan-scoped; it says nothing about aggregation window, caching, or rate limits.

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 short sentences with the returned metrics front-loaded and the scope qualifier last. No filler or redundancy.

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?

An output schema exists, so return values need not be spelled out, and a zero-param aggregate tool needs little else. The only residual gap is that the description does not disambiguate this tool from the several similarly named runtime/stats siblings.

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 nothing for the description to disambiguate; baseline 4 applies. The description invents no spurious inputs and correctly presents the tool as parameterless.

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 ('get ... runtime JavaScript fingerprints') and names the concrete outputs (coverage percentage, unique composite hashes, signatures). The closing clause distinguishes it from per-scan tools, but it does not separate itself from close siblings like get_js_runtime_stats or get_js_runtime_health.

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?

'Describes the service, not a scan' implies the aggregate scope, which is useful routing context against per-scan siblings. However, there is no explicit guidance on when to choose this over get_js_runtime_stats or get_js_runtime_behaviour, which have overlapping names.

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