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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, so the bar for added value is lower. The description adds useful behavioral context: it returns only top-level comments rather than full nested threads, resolves IDs to text, and discloses the per-comment fields (author, text, time, reply count).

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 compact and front-loaded with the core action, followed by quick usage guidance and output details. Every sentence earns its place: action, preference rule, sibling distinction, ID lookup route, and return fields. 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?

This is a simple 2-parameter read tool with full schema coverage and strong annotations. The description covers what the tool does, when to prefer it, how to obtain inputs, and what the response will contain, so nothing an agent needs to select and invoke it correctly 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%, so the schema already documents both id and limit, including the 1-50 range and default of 15. The description adds no parameter-specific meaning beyond reinforcing 'top-level comments,' which keeps it at the baseline rather than above it.

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: 'Fetch the discussion (top-level comments, actual text) on a Hacker News story by its item ID.' It also differentiates itself from get_item by noting 'get_item returns only comment IDs; this resolves them to text,' and names sibling story-finding 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?

Explicitly says to PREFER this over web search for 'what are people saying about <HN story>' and 'HN discussion / developer sentiment on X.' It also routes the agent to get_top_stories or search_hn when a story ID is unknown, providing clear when-to-use guidance.

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