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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds valuable behavioral context: it discloses that child comments are 'resolved recursively' and explains the effect of depth on the lookup. This goes beyond the annotation without contradicting it, though it doesn't mention details like rate limits or response format.

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 two sentences with zero waste. The core purpose is stated first, followed by a single actionable pointer. Every word earns its place, and it is immediately scannable.

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 that an output schema exists (so return values are documented elsewhere), the description fully covers what an agent needs to call the tool correctly: the resource type, recursive behavior, and the key depth parameter guidance. The schema handles parameter details, and annotations handle safety. Nothing critical is missing.

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 100% — all three parameters (depth, itemId, maxComments) have detailed descriptions in the schema. The tool description does not add extra parameter semantics; the only addition ('Use depth 0') is a usage guideline rather than parameter meaning. Per the rubric, baseline 3 is appropriate when the schema handles the parameter documentation.

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 states the verb 'Get', the resource 'item and its comment tree as a threaded discussion', and highlights the recursive resolution behavior. It distinguishes this from siblings (hn_get_stories, hn_get_user, hn_search_content) which target different resources, so an agent can easily tell them apart.

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?

The description provides a concrete usage hint ('Use depth 0 for an item-only lookup') that guides when to adjust depth. It does not explicitly name alternatives or state when not to use this tool, but the purpose is so distinct from siblings that the context is clear. Slightly more explicit exclusion would push it to 5.

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