mx_check

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It adds useful detail about output (priority ordering, resolved IPs) and the configurable DNS server default, but it does not explicitly state that the tool is read-only or non-destructive, nor does it mention any failure modes or prerequisites. Some transparency exists but gaps remain.

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: a clear purpose statement followed by a compact parameter listing. No wasted words, front-loaded with the main verb and resource. It is appropriately sized for a simple, focused tool.

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 simple DNS lookup tool with an output schema (not shown but present), the description covers the core functionality and all parameters. It lacks explicit usage scenarios or limitations, but given the straightforward nature of the tool and the presence of an output schema, the description is nearly complete. A small deduction because there is no mention of edge cases (e.g., nonexistent domain, timeout) or expected output format beyond the schema.

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 input schema provides only types and a default for dns_server, with no descriptions. The description compensates by explaining each parameter with a concrete example for domain and clarifying the default behavior for dns_server. This adds meaning beyond the schema, though for a simple two-parameter tool it does not need to do much more.

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 ('Look up') and a clear resource ('MX records'), and adds scope ('with priority ordering and resolved IP addresses'). This distinguishes it from siblings like dns_lookup, spf_check, and dmarc_check, which target other DNS record types or checks.

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 implies use for MX record lookups but does not explicitly state when to choose this over dns_lookup or other sibling tools. There is no exclusion or alternative guidance. The purpose is clear but the 'when-to-use' guidance is only implicit.

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