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

The annotations already declare readOnlyHint: true, so the tool's read-only nature is established. The description adds value by specifying the exact fields returned per story (title, URL, score, author, comment count), which goes beyond what the annotation conveys. It also consistently describes a fetch operation, showing no contradiction with the annotation. This supplemental behavioral detail is useful for the agent.

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 a single, concise sentence that front-loads the action and resource, then provides the essential details (feed types and return fields) without extraneous information. Every word contributes to the tool's purpose, and it is immediately scannable. This is an exemplar of efficient, structured description.

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 format is structurally defined), the annotations cover safety, and the input schema fully documents all parameters, the description supplies sufficient context for correct invocation. It covers the feed varieties and the nature of the returned data, and there are no hidden prerequisites or side effects to disclose. The tool is simple and the definition is complete for an agent to use it correctly.

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?

Since schema description coverage is 100%, every parameter (feed, count, offset) is already documented in the input schema with clear descriptions, including the enum values for feed. The description itself does not add significant semantic value beyond restating the feed types, which are already in the schema. This matches the baseline of 3 for full schema coverage.

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 explicitly states the action (fetch stories), the resource (HN feed), and the specific feed types (top, new, best, ask, show, jobs), while also listing the returned fields (title, URL, score, author, comment count). This clearly distinguishes it from sibling tools like hn_get_thread or hn_get_user, which target different resources. The purpose is unambiguous and highly specific.

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 implies usage by enumerating feed types and returned fields, but it does not explicitly state when to use this tool versus alternatives like hn_search_content or hn_get_thread. There are no exclusions or scenario-based guidance, leaving the agent to infer appropriate usage from the tool's name and description. This is adequate but lacks explicit routing.

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