spf_check

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

With no annotations, the description carries the burden of behavioral disclosure. It reveals that the tool checks syntax, counts DNS lookups, warns about the 10-lookup limit, and identifies common errors. This adds significant context beyond the schema and is more than a generic read-only hint.

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 clear sentences followed by a compact parameter list. Every sentence adds value, with no filler or redundant information. The structure is front-loaded with purpose and behavior.

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?

Given the tool's simplicity (2 params, 1 required), the description covers purpose, behavior, and parameters sufficiently. An output schema exists, so return format doesn't need to be in the description. The warning behavior regarding DNS lookups is an important detail that makes it complete for practical use.

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 has 0% description coverage, but the description provides meaningful semantics for both parameters: domain with an example and dns_server with its default. This fully compensates for the schema's sparse property documentation.

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 'Retrieve and validate the SPF record for a domain' with specific verb and resource, and lists specific validation behaviors (syntax, DNS lookup counting, common errors). This distinguishes it from sibling DNS tools like dns_lookup or mx_check.

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 usage for SPF validation but does not explicitly mention when to use it over alternative tools or exclude other cases. No alternatives are named. The clear scope gives some guidance, but not explicit when/when-not.

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