Email DNS Preflight x402

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely non-structured behavioral context: a paid call at $0.001 native USDC on Base, and that the recursive SPF analysis is bounded (a performance/scope limit) with deterministic suggested fixes rather than open-ended output.

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 tight sentences that front-load the scope of analysis and then the cost. Dense but every clause (checks performed, bounded recursion, deterministic fixes, price) carries information an agent needs.

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?

For a one-parameter diagnostic with no output schema, the description conveys what is analyzed, that recursion is bounded, that fixes are deterministic suggestions, and that the call is paid. It stops short of describing the shape of the returned findings, which is the only notable gap.

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 0% for the single 'domain' parameter, but the parameter name and the tool's framing make its meaning self-evident; no format, subdomain, or TLD constraints are clarified beyond minLength/maxLength. Marginal value over the schema, so a baseline 3 is fair.

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 concrete resources and checks (SPF/DMARC/DKIM/BIMI diagnostics, CAA/DNSSEC context, recursive SPF resolution), so an agent knows this is a domain email-authentication audit rather than a generic DNS lookup. It never names or contrasts the siblings (domain_preflight, email_preflight, domain_rdap), so differentiation is left to inference.

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?

There is no statement of when to pick this over email_preflight or domain_preflight, nor any prerequisite or exclusion. Usage is only implied by the topic words, which is insufficient given three plausible sibling diagnostics.

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

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds a meaningful behavioral detail beyond the annotations: it costs $0.001 native USDC on Base, which affects invocation. It does not explain payment mechanics, auth needs, or rate limits.

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 front-loaded sentences with zero waste: the first lists the inspection scope and the second states the cost. Every clause earns its place and nothing is buried.

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?

For a tool with overlapping siblings and a paid invocation, the description omits essential routing guidance and parameter semantics. It never clarifies when to use this versus domain_email_security, domain_rdap, or email_preflight, nor does it explain the domain argument, leaving the agent under-informed for correct selection and invocation.

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 0% for the single required 'domain' parameter, so the description must compensate but does not mention the parameter at all. It gives no format, scope, or example for the domain input, adding no meaning beyond the schema's type and length constraints.

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?

States a specific verb ('Inspect') and enumerates the exact resources checked (DNS, CAA, SPF/DMARC/DKIM/BIMI, DNSSEC, RDAP, registrar-lock, nameserver redundancy). However, it does not distinguish this broad preflight from the overlapping sibling tools domain_email_security, domain_rdap, or email_preflight.

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 gives no when-to-use guidance, no conditions for choosing this over siblings, and no exclusions. It only states what is inspected and the cost, leaving the agent to infer that this is a comprehensive preflight rather than an email-specific or RDAP-specific tool.

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

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

Annotations already cover the read-only, idempotent, non-destructive profile, and the description adds genuinely new context: it is privacy-safe and costs $0.001 native USDC on Base, which tells an agent a payment step is involved. It stops short of describing payment failure handling or rate limits, so it falls one notch below the top.

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, with the capability statement front-loaded and the cost constraint second. Every clause earns its place.

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?

For a one-parameter lookup with no output schema and solid annotation coverage, the description covers what is returned and the payment requirement. Minor gaps remain around input format expectations and error/refund behavior on a paid call.

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?

With a single required 'domain' parameter at 0% schema description coverage, the description must carry semantics, and it only implicitly identifies the input as a domain. It never clarifies accepted format (registrable domain vs subdomain vs IDN) despite the schema imposing min/max length bounds.

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?

States a specific verb ('lookup') and resource ('RDAP/WHOIS-successor') and enumerates the exact payload (age, expiry, registrar, statuses, nameservers, DNSSEC) so an agent can distinguish it from domain_email_security and the *_preflight siblings without opening a 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?

The enumerated return fields imply the use case (registration/DNS delegation data, not email-auth checks), but there is no explicit when-to-use or when-not-to-use guidance and no sibling named as an alternative. Usage is left to inference.

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

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

Annotations already establish read-only, idempotent, non-destructive behavior, so the safety profile is covered. The description adds genuinely new context beyond the schema: a per-call cost of $0.001 native USDC on Base, and an explicit disclaimer that no mailbox-existence claim is made. It omits any hint about result shape or latency.

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 tight sentences, zero filler, with the capability statement front-loaded and the scope caveat and cost trailing. Every clause carries information an agent needs.

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?

No output schema exists, so the description should ideally characterize what comes back (DNS records, authentication results, a posture verdict) but does not. Scope, cost, and safety are adequately conveyed; the return-value gap and the single undocumented parameter leave it only minimally complete.

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?

One required 'email' parameter with 0% schema description coverage; only minLength/maxLength constraints are machine-readable. The phrase 'practical email syntax' signals that input is validated rather than strictly RFC-parsed, which adds mild meaning, but nothing about accepted formats or normalization.

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?

Names specific verbs (validate syntax, inspect DNS, mail routing, authentication, domain-security posture) and the resource is unambiguous. It also delimits scope against the sibling concern 'domain_preflight' by being email-scoped, though it never names a sibling explicitly.

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 clause 'DNS-level only; no SMTP mailbox-existence claim' tells the agent what this tool will not answer, which is useful routing guidance away from an expected-but-unavailable capability. There is no explicit statement of when to pick this over domain_email_security or domain_preflight, so usage is only implied.

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