check_blacklist

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

The description discloses that the tool is read-only, requires no authentication, and handles provider timeout/availability gracefully by reporting unavailable and disabled providers. This complements the annotations (readOnly, idempotent) with concrete behavioral details.

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 dense but each sentence provides essential information, including purpose, input constraints, output characteristics, and usage context. It could be slightly more concise, but the structure is logical and front-loaded with the core function.

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?

The description covers the tool's function, input requirements, output details (including severity and removal metadata), and caveats (timeouts not misreported, not a delisting service). It is complete for the given schema and annotations.

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 description explains that the domain parameter resolves MX IPv4 addresses for checking, while the IP parameter allows direct checking. It also clarifies that at least one is required, adding meaningful context beyond the schema's basic field descriptions.

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 clearly states that this tool performs read-only queries against DNSBL/RBL providers to check blacklists. It also specifies the use case for mail-server reputation triage, distinguishing it from other tools like SPF or DMARC checkers.

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 explicitly says when to use the tool (mail-server reputation triage) and what it is not for (delisting). It also provides input requirements (either domain or IP, at least one required) and notes that noisy providers are disabled, giving clear usage guidance.

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