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

Annotations include readOnlyHint=true, which already signals a safe read operation. The description adds context beyond that by mentioning the official API and specifying the return format (titles, authors, dates, abstracts). It does not cover rate limits or errors, but given the annotations, this is sufficient.

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?

The description is two concise sentences. The first states the purpose and API usage, the second explains input options and output. Every word earns its place, and key information is front-loaded.

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?

With only one parameter, no output schema, and simple behavior, the description is complete. It explains the input format, the output fields, and the API source. No critical details are missing for effective use.

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?

The schema has 100% coverage for the single 'url' parameter, with a description that already explains it can be a search query or a full arXiv API URL. The main description repeats this information without adding significant new meaning, so it meets the baseline of 3 but does not exceed it.

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 clearly states the tool's function: "Search arXiv for research papers via the official API." It uses a specific verb ('search') and resource ('arXiv'), and distinguishes itself from sibling tools by naming the source. The return fields are also specified, leaving no ambiguity.

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 description provides clear context for use: it searches arXiv for research papers and accepts either a topic or a full arXiv API URL. It does not explicitly mention alternatives or exclusions, but the name and description make it obvious when to use this tool over siblings like extract_scholar or extract_reddit.

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