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

Annotations already provide readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds behavioral details beyond that: it returns a list (not a single item), supports pagination via page/pageSize, and clarifies that it fetches only top-level jobs from the thread. This goes beyond the annotations, though it does not detail output structure or rate limits.

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 sentences, front-loaded with the core function and pagination note. No filler, no redundancy. The description is appropriately sized for the tool's simplicity.

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 list tool with no required parameters and no output schema, the description explains the thread scope, pagination, and return type. It doesn't disclose the structure of each job listing, but given the simplicity and the presence of readOnly/openWorld annotations, it is sufficiently complete for an agent to call it correctly. Minor gap: no explicit mention of what fields each job row contains.

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 all four parameters have descriptions. The tool description only reiterates pagination and month selection, adding no new semantic info beyond what the schema already provides. Per the rubric, this earns the baseline score of 3.

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 and resource: 'List top-level jobs from the monthly Hacker News Who is Hiring thread'. It also specifies the optional month and distinguishes this tool from generic Hacker News listing tools like hackernews_feed_list or hackernews_story_comments_list by naming the specific thread type.

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 clear context on when to use this tool: specifically for the monthly Who is Hiring thread, with an optional month parameter to pin a particular thread. It does not explicitly name alternatives or exclusions, but the purpose is unambiguous enough that an agent would know to choose this tool over generic Hacker News feed or comment listers.

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