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

Annotations already declare readOnly/idempotent/no-destructive/openWorld, so the safety profile is covered. The description adds genuinely useful context beyond the schema: pay-per-call pricing with 10 free/day, the payment-required result shape, and that failed calls (isError) are not charged. It doesn't cover rate limits or latency, but this is well above the annotation bar.

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?

A single tight paragraph that front-loads purpose before capability details, then pricing and error semantics at the tail. Operationally important facts are packed densely without filler, though the return-field list is somewhat redundant given the output schema exists.

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 read-only search tool with a full output schema and complete parameter documentation, everything an agent needs is present: what it searches, how to narrow results, cost per call, free tier, and failure behavior. Nothing material 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 every parameter (days, sort, type, limit, query, min_points) is already documented, and defaults/ranges are explicit. The description restates the filtering dimensions but adds no syntax or format detail beyond the schema; the baseline 3 applies. It omits 'limit' entirely.

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 Hacker News stories and comments by keyword') plus the data source ('Algolia's official HN search'). An agent can distinguish it instantly from unrelated siblings like web_read or github_repo, and it names the sortable/filterable dimensions up front.

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?

Gives clear usage context ('what developers are saying about anything') and the conditions that shape a call (time window, minimum points, relevance vs date). It never names an alternative tool or states a when-not-to-use condition, so it stops short of full routing guidance.

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