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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful operational context beyond that: a $0.01 USDC x402 payment per successful call and a mirror HTTPS endpoint, both critical for an agent deciding whether to invoke and how. It omits rate limits and failure/payment-refund behavior.

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, each earning its place: returns first, query modes second, commercial/logistics third. Front-loaded and zero filler.

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?

No output schema exists, and the description compensates by listing the returned fields and links explicitly. With price, endpoint, query syntax and response fields all covered, an agent has enough to call it correctly and predict the result.

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 100%, so the schema already documents query, sort, limit, start and category with examples. The description restates the field syntax and category/sort options but adds no new syntax or formatting detail beyond the schema — 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 (Search) and resource (arXiv papers) and enumerates the exact return fields (title, authors, abstract, categories, dates, DOI/journal ref, abs + PDF links). This makes it immediately distinguishable from scholarly siblings like pubmed_search and openalex_search by source.

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?

Explains the two query modes (plain keywords vs field syntax ti:, au:, abs:, cat:, AND/OR) plus optional category filter and sort, which tells an agent how to use it. It stops short of naming alternatives such as openalex_search or pubmed_search for non-arXiv corpora, so no explicit when-not guidance.

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