check_rbl

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

Annotations already declare readOnlyHint and idempotentHint, so safety profile is known. Description adds the behavior of resolving MX hosts to IPs first. However, it does not disclose cache behavior (despite force_refresh parameter), rate limits, or what happens if no MX records exist. Adds some value but not comprehensive.

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, no verbose or redundant text. Front-loaded with the core purpose. Every sentence adds value.

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 an output schema present, the description does not need to detail return values. It covers the main process (resolve MX, check blocklists). However, it could briefly mention what the output indicates (e.g., blacklisted or not) or handle edge cases like missing MX records. Mostly adequate given schema richness.

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 coverage is 100% with all three parameters described. The description does not add meaningful information beyond what the schema already provides for any parameter. Baseline 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?

Description clearly states the tool checks MX server IP reputation against 7 named DNS-based Real-time Blocklists and mentions resolving MX hosts to IPs. It distinguishes from siblings like check_mx (which checks MX records) and check_mx_reputation (which may have different scope).

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?

Description implies usage for reputation checking against specific blocklists but does not explicitly state when to use this tool over alternatives like check_dbl, check_mx_reputation, or other check_* tools. No 'when not to use' or comparison provided.

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