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

Annotations (readOnlyHint=true, idempotentHint=true, destructiveHint=false) already establish that this is a safe, non-destructive read. The description adds meaningful context beyond that: result composition (HTML-stripped comment text, parent story context, author, direct link), no auth required, and licensing. It doesn't mention rate limits or pagination behavior, but with annotations covering the safety profile, the added detail earns a 4.

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 sentences with zero fluff: purpose is front-loaded, followed by result contents and auth/licensing. Every sentence earns its place, and the structure makes the description easy to scan.

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 an output schema present, return values are already defined structurally, and annotations cover the safety profile. The description adds search scope (full HN history) and result composition, while pagination defaults are in the schema. It's complete for invoking the tool, though a pointer to sibling search tools for different relevance/recency needs would make it stronger.

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 three parameters (query, page, limit) are fully documented with types, defaults, and bounds. The description mirrors the query semantics but adds no new meaning beyond the schema, so the 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?

States a specific verb and resource: 'Search HackerNews comments by keyword', and describes what it finds (community opinions, technical insights, discussions). It clearly distinguishes its target (comments) from story/item tools, but doesn't explicitly differentiate itself from sibling hnalgolia.search.recent or hnalgolia.search.relevance, so it misses the top mark.

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?

There is no explicit guidance on when to use this tool versus related siblings. The description implies a full-history keyword comment search but does not state when an agent should prefer this over hnalgolia.search.recent or hnalgolia.search.relevance, nor does it mention any exclusions or alternative conditions.

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