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 non-structured context that the annotations do not carry: a per-call price of $0.002 USDC via x402, which is material to an agent deciding whether to invoke it. It does not mention ordering, result freshness windows, or behavior on empty results.

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, both load-bearing: the first gives purpose and scope, the second gives the cost constraint. Purpose is front-loaded with 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?

For a read-only, single-optional-parameter feed with an output schema available, the description covers purpose, scope and the paid-invocation requirement. Missing only minor operational details such as sort order or pagination, which an agent could reasonably want when deciding how to use limit.

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?

Only one optional parameter (limit) and schema coverage is 100%, with the schema itself documenting the max 50 and default 25. The description adds no syntax, format, or trade-off information beyond the schema, 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 resource and scope: newest arXiv submissions restricted to the q-fin category, which cleanly separates it from arxiv__recent (general) and the other arxiv__recent-* category tools. The parenthetical expansion of q-fin removes any ambiguity. It stops short of explicitly naming the sibling it differs from, so it is clear but not fully self-differentiating.

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?

Usage is implied by the name and the word 'newest' — an agent can infer this is the recency feed for quantitative finance — but there is no explicit when-to-use, when-not-to-use, or pointer to alternatives such as arxiv__recent or arxiv__search. The agent must infer the selection rule from the tool name alone.

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