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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description adds genuinely new behavior: an API key is required and each call is metered as one blocklist download. It also discloses the result ordering (best first) and which fields come back, which annotations alone would not reveal.

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 short sentences with the payload description and ordering front-loaded, followed by the prerequisites and the alternative. Nothing is redundant and no sentence could be dropped without losing information.

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 no output schema, the description usefully lists the returned fields and ordering, and it covers prerequisites and quota cost, which is enough for a read-only list tool with fully documented parameters. Only minor details such as pagination behavior or what an empty result means are absent.

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 every parameter is already documented in the schema, and the description adds only the implicit notion of confidence ranking behind confidenceMinimum and the 'best first' ordering. That is marginal added meaning over the schema, so the baseline of 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 states a specific resource and its content: the highest-confidence abusive addresses, ordered best first, with score, country and categories included. That naturally distinguishes it from the single-entity siblings like check_ip and check_network, though it never names an alternative retrieval tool.

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?

It gives a clear usage boundary by naming an alternative path: for a firewall-ready file, point the firewall at the blocklist URL rather than calling this tool. It also signals the operational precondition (API key required) and cost (one blocklist download), but does not state when-not to use it beyond that single case.

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