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

With no annotations supplied, the description carries the full burden and does reasonably well: it discloses the credential model ('Uses the caller's OpenAny gateway credentials'), that charges and authorization are gateway-determined, the result cap (limit up to 100) and the 500-character abstract truncation. It does not cover rate limiting, error or empty-result behavior, or pagination beyond the single limit.

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 tight paragraphs: the first leads with what the tool returns and the key knobs, the second covers auth and billing. Sentences are dense but each carries information; the only slightly redundant part is re-listing fields the schema already enumerates.

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 single nested-body search tool with no output schema and no annotations, the description supplies return content, truncation rules, a result ceiling, credential handling and cost model. Little a caller needs in order to invoke it correctly 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 the schema already documents sort, limit, query and category, including defaults and bounds. The description's restatement of sort values, the cs.LG category example and the limit ceiling adds little beyond the structured data, so the baseline 3 applies.

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: 'Papers on arXiv that match a query, from the arXiv API', and enumerates the returned fields. It is unambiguous which resource this hits. It does not name or contrast any alternative search tool, but no sibling in the catalog covers arXiv, so confusion risk is low.

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 never says when to choose this over other search tools (e.g. google_scholar, serper_post_scholar, or generic web search) or what preconditions apply beyond gateway credentials. The only conditional guidance is on parameter values ('sort is relevance or date'), which is setting configuration rather than when-to-use.

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