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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the description carries a lighter burden. It adds that this maps to a public API endpoint (GET /v1/runtimes), suggesting no auth/account scoping, but discloses nothing about return shape, ordering, or caching.

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, front-loaded with the resource and its contents, with the API endpoint as a compact trailing note. No filler and nothing redundant.

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-parameter, read-only list tool with no output schema, the description gives enough to call it and understand roughly what comes back (Node versions plus bundled dependencies). A brief note on return format would make it fully complete, but the essential context is present and consistent with the annotations.

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. Schema coverage is 100% and the empty object schema is consistent with the description's no-argument claim.

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 (List) and resource (runtimes), and disambiguates the resource by spelling out what a runtime contains (Node versions + bundled dependencies) and the check types it applies to. It does not name a sibling to distinguish from, but the resource is unique among the sibling tools.

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?

Usage is only implied — an agent infers it should call this to discover available runtime versions, and 'for browser/API checks' hints at the context. There is no explicit when-to-use, no prerequisites, and no when-not-to-use guidance or alternative tool mentioned.

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