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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds extra behavioral context: the result cap ('Up to 20 stories'), the exact returned fields, the lack of auth requirements, and the data licensing attribution. This goes beyond the structured annotations without contradicting them.

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?

Three tightly scoped sentences with no filler: the first defines what the tool returns and how stories are selected, the second lists result fields and the cap, and the third covers auth and licensing. Every sentence earns its place and the key information is front-loaded.

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 simple, read-only, single-optional-parameter tool with an output schema and safety annotations, this description is complete. It covers selection criteria, result contents, maximum count, auth requirements, and licensing. Nothing an agent needs to correctly invoke this tool 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 fully documents the `limit` parameter with min, max, and default. The description's mention of 'Up to 20 stories' reinforces the max but does not add new semantic detail beyond what the schema provides. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'Fetch the best-rated stories from Hacker News.' It further clarifies the selection mechanism ('best feed algorithm which balances score, engagement, and editorial quality') and lists the returned fields. This clearly differentiates it from sibling tools like hackernews.stories.top and hackernews.stories.new.

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 gives clear context: this is the tool for high-quality, algorithmically selected HN stories, and it explicitly states 'No auth required.' It does not explicitly name sibling alternatives or when-not-to-use cases, but the 'best feed' framing makes the intended use apparent.

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