flatten_spf

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

Beyond the annotations (readOnly, idempotent, non-destructive), the description adds 'No auth, no side effects' and cautions about high maintenance and provider IP rotation. These traits are not in the annotations and add valuable context.

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 somewhat lengthy but packs essential details: purpose, usage, return content, and caveats. It is well-structured with a logical flow, though it could be slightly more concise without losing nuance.

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 operation's purpose, output details (lookup counts, IP count, record length, split flag, maintenance warning), and practical advice. It is complete given the lack of an output 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 schema already fully describes the sole parameter 'domain' with a clear description. The tool description adds no additional meaning about the parameter, so it stays at the baseline for full schema coverage.

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 the tool's function: it flattens SPF records by resolving the full include/a/mx/redirect graph to literal IP addresses, returning a single SPF record within limits. This distinguishes it from sibling tools like check_spf or generate_spf.

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?

Explicit usage guidance is provided: 'Use when a domain hits too many DNS lookups (PermError) and removing unused includes is not enough' and references running check_spf first. This clarifies when to choose this tool over alternatives.

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