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

Annotations only declare readOnly and openWorld, so the description carries real weight and delivers: ordering (newest first), a concrete cost signal ('Costs 1 credit'), and the return shape — points and comment counts for stories, comments as plain text keyed to their item page URL. That is meaningful operational context beyond the annotations. It stops short of describing result limits or how pagination terminates.

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?

Four short sentences, dense and mostly front-loaded — ordering and cost land early, return shape follows. The opening 'Search.' fragment adds nothing and duplicates the name and title, but the remainder has no waste.

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?

With no output schema, the description must convey return shape, and it does (scores, comment counts, plain-text comment bodies, item URLs). Credit cost is also disclosed. The main remaining gap is pagination behavior given the cursor parameter; everything else an agent needs to call this correctly is present.

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 coverage is 75%, so the schema already documents query, type (with enum), and cursor. The description reinforces the type distinction by explaining what stories vs comments return, but says nothing about cache_max_age, the one undocumented parameter, nor about cursor semantics. Baseline 3 is appropriate when the schema does the heavy lifting.

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 names a specific verb (search) and a specific resource (Hacker News stories and comments), plus the ordering guarantee 'newest first'. It is clearly distinguishable from reddit_search, bluesky_search and the other search siblings by resource. The leading fragment 'Search.' is redundant with the title, and no sibling is named explicitly, keeping it from a 5.

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?

Usage is implied rather than stated: an agent infers 'this is the Hacker News search tool' from the resource naming, and the type values (story/comment/all) hint at scoping choices. There is no explicit when-to-use, when-not-to-use, or pointer to an alternative tool for adjacent needs (e.g. fetching a post's replies).

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