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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the safety profile is covered. The description adds little beyond that: it restates what the record contains (which the output schema already defines) and says nothing about behavior on an unknown or malformed id.

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?

A single front-loaded fragment with no filler, and the payload list is ordered usefully. It is efficient but is a noun phrase rather than a sentence, so the action is never phrased.

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?

Because an output schema exists, the description needn't enumerate return fields, yet that is almost all it does. For a simple one-param lookup this is adequate, but it leaves out the one useful addition: that the arxiv_id should come from a prior search/list call.

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% with a single documented arxiv_id (format example, maxLength), so the schema carries the parameter semantics entirely. The description never mentions the id, adding no meaning 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?

"One paper" plus the enumerated payload (abstract, authors, fields, code/model flag, links) makes clear this fetches a single paper record, which is distinguishable from list-oriented siblings like latest_papers and search. It lacks an explicit verb (fetch/retrieve), so the action is inferred rather than stated.

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?

There is no statement of when to use this versus search, latest_papers, or trending, and no mention that it requires a known arXiv id. The agent must infer routing from the name alone.

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