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

Beyond the readOnlyHint annotation, the description discloses meaningful behavior: indicators are matched exactly, defanged input is refanged first, and only scans the current token can read are searched. This gives an agent important operational expectations without contradicting the annotations.

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?

Three sentences deliver the core purpose, accepted input scope, matching behavior, and access boundary with no filler. The most important information is front-loaded, and every sentence contributes operational meaning.

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 a read-only list/search endpoint with only two simple parameters and a provided output schema, the description covers purpose, accepted indicator types, matching semantics, defang handling, and authorization scope. Nothing needed for correct invocation 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?

The schema already provides 100% coverage for both parameters, including the type enum and indicator meaning. The description adds value by clarifying exact-match semantics and defang/refang handling for the indicator parameter, which is not present in the schema.

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 uses a specific verb ('Find scans where an indicator was observed') and identifies the resource (scans) plus the full range of accepted indicator types (IP, domain, URL, mutex, registry key, hash, JA3/JA4). This clearly distinguishes the tool's core purpose from the sibling 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?

The description conveys that this tool is for searching scans by an observed indicator and notes that only readable scans are searched. However, it does not explicitly say when to prefer this over lookup_hash or other siblings, nor does it state any exclusion conditions, leaving some routing to inference.

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