User agents seen on an IP

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: pagination behavior, the paid-plan requirement and its error consequence, and the fact that results are observed data with first/last seen dates. This goes beyond the annotations without contradicting them.

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 with no filler. The core action and resource are front-loaded, followed by the pagination note and the plan requirement. Every sentence earns its place.

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, paginated list tool with a fully documented schema, the description covers the essential context: what is returned, pagination, and the paid-plan constraint. It doesn't describe the exact response format, but there is no output schema and the response_format parameter lets the caller choose. The absence of an output schema is a minor gap, but the description is otherwise complete for an agent to decide whether to call it.

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 the schema already documents all three parameters. The description adds the context that each page costs one API query, which is useful for the 'page' parameter, but it doesn't add much beyond the schema. Baseline 3 is appropriate.

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 states a specific verb ('List'), a specific resource ('user-agent strings SecurityTrails has observed originating from one IPv4 address'), and includes the temporal fields ('first and last seen dates'). It clearly distinguishes from siblings like securitytrails_ip_neighbors or securitytrails_ip_whois by focusing on user agents observed on an IP.

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 mentions pagination and the paid-plan requirement, which gives context on when it can be used. It doesn't explicitly name alternatives or say when not to use it, but the sibling list and the specific resource make the use case clear. The plan error note is a useful exclusion for free-tier users.

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