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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is fully covered structurally. The description adds genuinely non-obvious behavioral context beyond that: a per-call cost of $0.002 USDC via x402, which materially affects whether an agent should invoke it. It does not describe pagination or result volume, but the output schema carries the return shape.

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 tightly written sentences, front-loaded with the core capability and followed by the sorting options and the cost caveat. No filler, and the pricing detail earns its place because it is not available in any structured field.

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?

An output schema exists, so the description need not explain return values, and annotations fully cover the safety profile. What is supplied — query dimensions, sort semantics, and cost — is sufficient to invoke the tool correctly; only pagination behavior for start/limit is left to the schema, which is acceptable.

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 already has documentation and the baseline is 3. The description restates the searchable dimensions (keywords, title, author, category) and mentions relevance-vs-newest sorting, but adds no syntax, format, or constraint detail beyond what the schema entries ('all must match', 'max 50', 'default 20', 'cs.CL') already provide.

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?

The description states a specific verb and resource ('Search arXiv') and enumerates the searchable fields (keywords, title, author, category), which distinguishes it from retrieval siblings like arxiv__paper and the arxiv__recent-* feeds. It stops short of explicitly naming those siblings, so an agent must infer the boundary rather than being told it.

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 verb 'search' and the enumerated query fields, so an agent can reasonably conclude this is the general query tool. However, there is no explicit statement of when to prefer this over arxiv__paper or the topic-specific arxiv__recent-* tools, and no exclusions or prerequisites are given.

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