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

No annotations are provided, so the description carries the full behavioral burden. It discloses the read-only, DNS-only nature of the operation, the recursive traversal behavior, the RFC 7208 limit being evaluated, and what it returns (flattened include tree, total lookup count, warnings on excess, loops, void lookups). It does not mention performance or query-volume implications of the recursive lookup, but otherwise provides strong transparency for a read-only tool.

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?

Two dense sentences plus a short read-only/DNS-only tag, front-loaded with the core action and scope. Every clause adds information (recursive traversal, limit, failure mode, return values, safety), with no wasted wording.

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 complexity (recursive DNS traversal with loop/void detection) and the absence of both annotations and an output schema, the description supplies the missing return-value shape and safety profile (read-only, DNS-only) and names the key domain semantics. An agent has everything needed to select and invoke it correctly.

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%: the lone 'domain' parameter is already documented in the schema as 'Domain to query, e.g. example.com'. The description adds no additional parameter syntax, format constraints, or edge-case semantics beyond what the schema provides, so the baseline 3 applies.

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 names a specific verb and resource (recursively expand a domain's SPF record) and a precise scope (follow every include: and redirect=, count DNS-lookup mechanisms across the WHOLE tree against the RFC 7208 limit of 10). It explicitly distinguishes itself from the sibling tool spf_check by naming the failure mode spf_check misses, so an agent can tell the two apart without opening either schema.

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?

It names the alternative (spf_check) and the exact condition that selects this tool instead: nested includes quietly push the total over 10 and the record hits permerror. That is an explicit when-to-use vs. alternative statement, leaving little to inference.

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