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

With no annotations, the description carries the full burden and does so: it discloses the current data limitation (only CVE identifiers, so most lookups return found:false), the exact result shapes for found/not-found, the fact that not-found is never an error and does not mean 'safe', the free-vs-paid payment model (x402, PAYMENT-SIGNATURE header, Gumroad key), and the failure shape with isError and structuredContent. This is unusually complete.

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 the core purpose and structured under explicit SIBLING DIFFERENTIATION and BEHAVIOR labels, which aids scanning. It is dense and somewhat long, but nearly every sentence carries non-redundant information given the absence of annotations and output schema.

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?

No output schema and no annotations exist, so the description must cover return values and operational behavior — and it does, including result shapes, payment triggers, and error handling. Nothing an agent needs to invoke this correctly is missing.

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% and there is a single required parameter, so the schema already documents the value format thoroughly. The description reinforces the accepted indicator types but adds no syntax or format detail beyond the schema, 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 a specific verb (looks up) and resource (a single indicator value) and names the exact scope: IP, domain, URL, or hash. It explicitly contrasts itself against get_ioc_batch, get_threat_indicators, and get_cve_details, so an agent can route correctly without opening any schema.

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?

Gives explicit when-to-use ('recommended pre-action safety check before visiting, downloading, or connecting') and when-not-to-use with named alternatives for bulk, multi-indicator, and vulnerability cases. The conditions that select each sibling are spelled out.

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