check_rbl

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations: it resolves MX hosts to IPs first and checks six named blocklists, which helps the agent anticipate the operation's flow and scope.

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?

The description is two sentences with no filler. The primary action and key scope ('MX server IP reputation', the six blocklists) are front-loaded, and the resolution behavior is stated succinctly in the second sentence.

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 a rich output schema, full parameter documentation, and safety-relevant annotations, the description covers the essentials for correct invocation. The only noticeable gap is the lack of guidance distinguishing this tool from the similarly named check_mx_reputation and check_dbl siblings.

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 domain, format, and force_refresh well. The description adds no extra parameter-level meaning beyond what the schema provides, so the baseline score of 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 uses a specific verb and resource ('Check MX server IP reputation') and names the exact six blocklists involved. It is clear about the tool's function, though it does not explicitly name sibling tools like check_dbl or check_mx_reputation to draw a distinction.

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 explains what the tool does but gives no guidance on when to choose it over similar siblings such as check_dbl, check_mx_reputation, or check_realtime_threat_feed. No exclusions, alternatives, or situational cues are provided.

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