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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered elsewhere. The description adds a genuinely new behavioral fact: a per-call cost of $0.002 USDC via x402, which an agent needs before invoking. It omits ordering/pagination behavior, so not quite a 5.

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 short sentences, purpose front-loaded, cost disclosure second. Zero filler and nothing repeated from the title.

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?

Return shape is covered by the output schema and safety semantics by annotations, so the description only needs scope plus cost — both present. Minor gap: it doesn't say whether results are ordered by submission date or include abstracts, but nothing essential to correct invocation 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?

Single `limit` parameter with 100% schema description coverage ("Results, max 50 (default 25)"), so the schema fully documents it. The description adds no format, ordering, or interaction detail beyond that, making the baseline 3 correct.

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 resource and scope: newest arXiv submissions in cs.CV. The category scoping (cs.CV) is what separates it from the twelve other arxiv__recent-* siblings, so an agent can pick the right one without opening the schema. It stops short of an explicit sibling reference (e.g. arxiv__search for keyword queries), keeping it at 4 rather than 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?

"The newest submissions in cs.CV" implies the use case (recency feed for computer vision) but gives no explicit when-to-use/when-not, no mention of arxiv__search for topic queries, and no prerequisites. Usage is inferable from scope alone, which is the definition of an implied-usage 3.

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