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

Beyond the readOnly/openWorld annotations, the description discloses concrete operational behavior: price ($0.002 USDC per successful call), payment rails (x402 on Base, Solana or Arc), and the billing rule that failed calls and unknown DOIs (404) are not charged. That is exactly the kind of cost and failure semantics an agent needs before invoking a paid tool.

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 sentences carry the resource definition, the alternative mode, the failure mode, and the pricing, with the primary behavior front-loaded and no 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?

With an output schema present, the description need not explain return values, yet it still lists the key fields. It also covers both modes, the 404 case, and the payment model, leaving nothing an agent needs in order to call this paid endpoint correctly.

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 all three parameters are already documented (doi example, q as citation search, limit 1-10 default 5). The description's 'max 10' merely restates the schema constraint and adds no new syntax or format guidance, 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?

The description names a specific resource (a DOI's Crossref bibliographic record) and enumerates the returned fields, plus a second mode (citation-style search returning up to 10 matches). An agent can tell what it fetches, but nothing distinguishes it from sibling literature tools like arxiv, pubmed, or research_papers, so it does not help routing among near-neighbors.

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 two modes are implied by 'or' and clarified by the schema (doi for a known identifier, q for a citation-style search), which is enough to choose the right parameter. However, there is no explicit statement of when to prefer this over arxiv/pubmed/research_papers, and no stated prerequisites or exclusions beyond the 404 note.

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