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

Annotations cover read/idempotent/openWorld, so the bar is lower, and the description adds the crucial non-annotation behavior: the x402 payment gate, the $0.005 price, and the fact that it returns payment requirements unless payment_signature is supplied. It doesn't describe the shape of successful paper results or pagination, keeping it from a 5.

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?

Front-loaded with a category tag, then purpose, then the agent trigger, with payment mechanics last. The price appears in both the title and description, a minor redundancy, but overall tight and well ordered.

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 an 8-param, no-output-schema tool, the description covers the critical payment-gated flow and points to a sample for the return format. The only gap is that the successful paper-search response shape isn't characterized, but the sample link offsets this.

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%, so every parameter (doi, type, limit, query, author, years, payment_signature) is already documented in the schema. The description adds no syntax or format detail beyond what the schema provides, 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 specific verbs and resources: 'Verify a citation or DOI, or find research papers on a topic,' and names Crossref as the backing source. No sibling tool covers research papers or DOI resolution, so an agent can distinguish this immediately from the sanctions/company/weather tools.

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?

'Use when an agent must check that a reference exists and is cited correctly' gives clear usage context and intent. It stops short of stating when to use the doi path vs. the query/author filters, but the primary trigger is unambiguous.

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