dns_email_security_checker

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

With no annotations, the description carries the full burden. It does disclose genuinely useful behavioral facts: results are scored, and cost is billed to the caller's own Apify account at ~$0.005 per result with lower paid-plan pricing. It says nothing about how non-resolving domains, timeouts, or partial failures are reported, which leaves real gaps for a network-probing 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 sentences, zero filler. The output enumeration is front-loaded in sentence one and the pricing caveat is deferred to sentence two, so an agent reads the capability before the commercial detail.

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?

There is no output schema, but the description compensates by enumerating the returned record types and stating the one-row-per-domain shape. Parameters are fully covered by the schema, so nothing needed for a correct call is missing.

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%, so the schema already documents all three parameters in depth (DKIM selector mechanics, cost trade-off of disabling checkDkim). The description adds no parameter detail beyond the general notion of supplying domains, 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 — it 'returns SPF, DKIM, DMARC, MX, MTA-STS, BIMI, CAA, nameservers, registrar and domain age' for each supplied domain, plus a scored row. That is far more concrete than the tool name alone, though it never distinguishes itself from the sibling domain_security_audit, which appears to overlap.

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?

Usage is implied by 'for every domain you give it — one scored row per domain', which makes the batch-report pattern obvious. There is no explicit when-to-use statement and no routing away from the overlapping domain_security_audit sibling, so an agent must infer the choice.

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