SPF Record Check

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

Annotations already provide readOnlyHint=true, destructiveHint=false, idempotentHint=true, openWorldHint=true. The description adds behavioral details beyond annotations: it detects missing/multiple records, trailing all qualifier, and counts DNS-querying terms recursively against RFC 7208 limit. No contradiction with annotations.

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 well-structured: purpose first, then bullet-like detections, then args and return format. It is front-loaded with purpose. The Returns block may be slightly redundant given the output schema exists, but overall concise.

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 complexity of SPF checking with nested lookups, the description covers key points: detection types, parameters, and return fields. Output schema exists (not shown but signaled). It lacks details on error handling or edge cases but is sufficient for an agent.

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% with clear descriptions for both parameters. The description re-iterates the parameters in Args block but does not add significant new meaning beyond the schema. Baseline 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 clearly states 'Fetch and analyse a domain's SPF record' and lists specific detections (missing/multiple records, trailing all qualifier, DNS lookup counts). The tool name 'spf_check' differentiates it from sibling tools like dkim_check, dmarc_check, etc.

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 includes an example usage: 'Does sendgrid.net's SPF exceed the 10-lookup limit? -> spf_check(domain="sendgrid.net")' and explains what it detects. However, it does not explicitly state when not to use it or compare to alternatives like email_auth_audit.

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