Disban

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

Annotations already cover the read-only/open-world safety profile, so the description earns credit for adding interpretation guidance beyond them: 'Unknown means not enough evidence, not safe.' It also discloses the response contents (reason, evidence, can-receive-mail), though it says nothing about latency, rate limits, or caching of domain lookups.

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 waste: the classification taxonomy and its caveat come first, usage context last. The category enumeration is dense but earns its place since no enum or output schema exists to carry it.

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?

With no output schema, the description must convey return semantics, and it does: category, reason, evidence, and deliverability. It also closes the main interpretive trap ('unknown' ≠ safe), leaving nothing an agent needs missing for correct selection and interpretation.

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?

Only one parameter, and the schema description coverage is 100% — the schema already documents the accepted forms with examples (person@example.com or example.com). The description restates the same accepted input without adding new syntax or format detail, 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?

States the specific verb 'Classify' and the resource 'domain of an email address or a bare domain', and enumerates the exact output categories (disposable, free, alias, testing, parked, unknown). The singular scope implicitly distinguishes it from the plural sibling check_email_domains, so an agent can route correctly.

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?

Gives a clear triggering context: 'Use before creating an account or sending a verification email.' It does not explicitly name the batch sibling check_email_domains or state when not to use this tool, so it stops short of full alternative routing.

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?

With readOnlyHint and openWorldHint already declared, the description adds genuinely new behavioral facts: results are returned in input order, and a failed entry carries an error and is not charged. The billing/charging detail is not derivable from annotations or schema and is directly useful for cost-aware usage.

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 short sentences, no filler. The core capability and the 50-item limit are front-loaded, and the ordering/billing caveat follows as the second most relevant fact.

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 read-only tool with no output schema, the description covers capacity, accepted input types, result ordering, and error behavior. The main missing piece is explicit routing to the singular sibling, but overall the agent has enough to call 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 0% and the single 'inputs' array is untyped beyond string items, so the description carries the load. It clarifies that entries may be email addresses OR domains and restates the 50-item cap, which meaningfully interprets the otherwise bare schema.

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 (classify) and resource (email addresses or domains) with the batch scope of up to 50 made explicit. It contrasts implicitly with the singular sibling check_email_domain, but never names it, so sibling differentiation is inferred rather than stated.

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 'up to 50 at once' framing implies this is the bulk variant to use when processing many entries, and the sibling check_email_domain exists for single lookups. However, no explicit when-to-use or when-not-to-use guidance is given, leaving the agent to infer the batch/single split.

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?

The readOnlyHint annotation already establishes this is a safe, non-mutating call, so the description is not carrying the safety burden. It adds the useful scoping detail that the count is monthly and self-resets, but says nothing about account/auth requirements, error behavior, or freshness of the figures.

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?

One short sentence with no filler, front-loading the most important return value (current plan). It is a verbless fragment, which reads slightly telegraphically but wastes nothing.

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?

With no output schema present, the description must hint at return contents, and it does list the three returned facts. For a zero-argument read whose safety profile is covered by annotations, that is adequate; only the exact units/format of 'checks' and the reset timestamp format remain unspecified.

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 tool takes zero parameters, so there is no parameter semantics for the description to compensate for; the baseline for a parameterless tool applies. The absence of a subjects/plan argument is worth noting but consistent with a single-account usage endpoint.

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 the concrete payload — current plan, remaining checks this month, and reset timing — so an agent knows this is an account-usage/quota read rather than a domain check. It does not explicitly contrast itself with the check_email_domain siblings, though the subject matter is distinct enough to infer the split.

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 call this versus any alternative, and no prerequisites or exclusions. A reader can infer it is a status/limits lookup, but the description gives no routing guidance at all.

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