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 useful behavior beyond that: it discloses the pricing model, that currencies are never combined, and that assumptions are returned. It does not say what happens for missing price data or how currency is selected.

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 cost model and the currency constraint front-loaded. Every clause carries information.

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 3-parameter read-only calculator with no output schema, the description covers the cost model, the currency constraint, and mentions returned assumptions. It is close to complete, though the return shape beyond 'assumptions' is left vague and no output schema exists to fill that 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%, so the description must carry parameter meaning. It does bound 'years' to 1-10 and identifies the registrar/TLD pair, but gives no format guidance for 'tld' (e.g., 'com' vs '.com') or 'registrar' (name vs ID), leaving real ambiguity.

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 (calculate), resource (domain ownership cost), scope (1-10 years, one registrar/TLD pair), and even the formula (year-1 registration plus subsequent current renewal prices). The 'one registrar/TLD pair' framing implicitly separates it from comparison siblings like compare_registrars and cheapest_registrar, though no sibling is named 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?

Usage is only implied by the stated scope: use this for a single registrar/TLD pair rather than a comparison. There is no explicit when-to-use, when-not-to-use, or alternative-tool routing against compare_registrars or cheapest_registrar, which are the obvious neighbors.

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 read-only, idempotent, open-world and non-destructive semantics, so the safety profile is free. The description adds two pieces of genuine context beyond that: ties are returned ('or tied registrars') and the upstream source is TLD-List v1 extension/getCheapestRegistrar. It says nothing about rate limits, auth, or result ordering.

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 with the core purpose front-loaded and no filler. The endpoint reference is arguably implementation detail an agent does not need, but it is short and adds provenance.

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 4-param read-only tool with full annotation coverage and no output schema, the description is adequate to select the tool but thin on invocation detail: registrar identifier format and include/exclude interaction are left to the schema, which documents neither.

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 coverage is 0%, so the description must carry the burden. It does reference all four parameters conceptually (TLD, price type, registrar include/exclude lists), but gives no format for registrar identifiers, no note on how include and exclude interact, and no clarification of the priceType enum values.

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+resource ('Find the cheapest registrar') plus the scope that defines it ('one TLD and one price type'). An agent can distinguish it from the compare_* siblings by scope, though no sibling is named 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 phrase 'for one TLD and one price type' implies this is the single-TLD lookup rather than a bulk comparison, which implicitly routes the agent away from compare_registrars/compare_tlds. However, no alternative is named and there is no explicit when-not guidance.

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 read-only, idempotent, open-world and non-destructive behavior, so the bar is lower; the description adds real value by naming the RDAP provider and, importantly, disclosing that a 404 result is explicitly non-authoritative and not a purchase guarantee. That caveat is exactly the kind of behavioral context annotations cannot express, though rate limits or provider failure behavior are not addressed.

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 tightly written sentences, front-loaded with the action and scope, followed by the result-interpretation rule. No filler or repetition of the title.

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 carries the burden of explaining return semantics, and it does so precisely: found record means registered, 404 suggests availability. The non-authoritative caveat closes the main interpretive gap for an agent reporting results to a user.

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 coverage is 100% and the single 'domain' parameter is fully documented with an example in the schema, so the schema does the heavy lifting. The description reinforces the 'fully qualified domain' expectation but adds no format, normalization, or edge-case detail beyond it.

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 gives a specific verb and resource (check a domain's availability) and scopes it to 'one fully qualified domain,' which implicitly contrasts with the plural/variant siblings like search_tld_variants and list_tlds. It stops short of naming an alternative or exclusion, 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?

It conveys that this is for a single FQDN and explains how to read the result (record = registered, 404 = likely available), which implies the use case. However, there is no explicit when-to-use vs. when-not guidance and no routing to siblings such as compare_registrars or search_tld_variants for related needs.

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 readOnly, idempotent, openWorld and non-destructive, covering the safety profile. The description adds useful behavioral context about what is returned (missing prices, promotions, terms, notes), which matters because no output schema exists, but says nothing about freshness or coverage limits of the pricing data.

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 dense sentence, front-loaded with the verb and the compared dimensions, with no filler. The trailing list of included data is a bit packed but each item earns its place given the absence of an output schema.

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 usefully enumerates the returned data elements, but leaves gaps on parameter defaults, limits, and registrar ID format, and offers no routing guidance among the pricing/cost siblings.

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 coverage is 0%, so the description must carry the parameter burden. It does map the price types (registration/renewal/transfer implied by wording) to priceTypes and 'registrar IDs' to registrars, but omits the default price-type set, the 50-registrar cap, and ID format expectations.

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 (Compare) and resource (registration, renewal, transfer pricing) with clear scope: one TLD across selected registrar IDs. This implicitly separates it from compare_tlds, which operates on the TLD axis, though no sibling is named 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 description says what is compared but gives no when-to-use guidance and names no alternatives, despite siblings like cheapest_registrar, compare_tlds, and calculate_domain_cost that could be confused with it.

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, openWorldHint and destructiveHint=false, so the safety profile is fully covered elsewhere. The description adds modest value by disclosing the batch ceiling and that results include documented TLD metadata, but says nothing about rate limits, data freshness, or how missing TLDs are handled.

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?

A single dense sentence with the key scope (batch, 100 cap) and the comparison dimensions front-loaded. Nothing is padded, though the trailing 'with documented TLD metadata' clause is vague and earns less than its space.

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 read-only tool with no output schema and 0% parameter coverage, the description covers the core purpose adequately but omits the semantics of the two registrar-filter parameters and gives no sense of the result shape beyond 'metadata'. It is minimum viable rather than 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?

Schema description coverage is 0%, so the description carries the full burden. It only hints at 'tlds' via the 'up to 100 extensions' phrasing and obliquely at 'years' via 'multi-year ownership cost'; the includeRegistrars and excludeRegistrars filters are never mentioned, leaving half the parameters undocumented in both places.

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 states a specific verb (batch-compare) and resource (extensions/TLDs) and enumerates the four cost dimensions being compared. It implicitly separates itself from compare_registrars and cheapest_registrar by scoping to TLD extensions, but it never names an alternative, so it falls short of a 5.

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 word 'batch' and the 'up to 100' cap imply this is the multi-TLD comparison tool rather than a single-lookup one, but there is no explicit when-to-use statement, no prerequisites, and no routing to siblings like compare_registrars or calculate_domain_cost.

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 non-destructive, covering the safety profile. The description adds two genuinely useful facts beyond that: results are restricted to *active* registrars and the return is IDs (not full registrar records). That's modest added context, not enough for a 4.

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, front-loaded with the action and scope, and ending with the actionable instruction about ID reuse. Nothing wasted.

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 simple, zero-required-param list tool with no output schema, the description conveys what is returned (registrar IDs) and the filtering/pagination behavior. It leaves the exact ID format and result ordering unstated, but that is a minor 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 coverage is only 33% (only 'query' is documented), yet the description merely alludes to 'substring filtering and pagination' without adding format, default, or limit/offset semantics. It adds no meaning beyond the schema, so it neither compensates for the coverage gap nor drops below the baseline.

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 and resource ('List active TLD-List registrar IDs') plus the scoping mechanisms (substring filtering, pagination), which separates it from list_tlds and the search/compare siblings. It doesn't explicitly name which sibling to prefer, so it stops short of a 5.

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?

'Use these exact IDs in other tools' gives downstream usage context, implying this is a lookup step feeding tools like check_domain or compare_registrars. However, it gives no guidance on when to use this versus list_tlds or search_tld_variants, 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.

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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds pagination and page-scoped metadata fetching, but omits the non-obvious default that TLDs without registrars are filtered out by default.

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?

A single, front-loaded sentence with no filler; the primary purpose leads and the qualifiers follow. Compact, though the capability enumeration is somewhat dense.

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 6 parameters, no output schema and only half the parameters described, the description should at least explain the default filtering behavior and the paged return shape. It covers the headline features but leaves the agent guessing about omitted defaults.

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 coverage is 50%: query, punycode and includeMetadata are already documented in the schema, and the description merely restates them. The undocumented limit, offset and omitWithoutRegistrars get no compensating explanation, so nothing meaningful is added beyond the 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?

Names a specific verb and resource ("List extensions supported by TLD-List") and enumerates the capabilities (substring search, pagination, punycode, metadata). An agent can tell it is the bulk-listing tool rather than a variant/registrar lookup, 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?

Usage is only implied from the capability list; there is no statement of when to prefer this over search_tld_variants or compare_tlds, and no prerequisites or exclusions. Adequate for retrieval, but the agent must infer 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?

Annotations already establish readOnly, idempotent, non-destructive, open-world behavior, so the description is free to add value — and it does: it discloses the return shape (separate cheapest registration, renewal, transfer, and same-registrar 3-year costs) and a hard API limitation (no popularity/ranking data in API v1). What it omits is any note on batching cost, latency, or what happens when a name has no available TLD.

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, front-loaded with the core action and followed by output and limitation facts; no filler. The 'intentionally unavailable' clause is longer than strictly needed but earns its place by preventing a wrong invocation.

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 describing the four return cost fields is necessary and done well. But for an 11-parameter, zero-required tool the description leaves key mechanics unaddressed: how name/names/tlds combine, default limit behavior, and the meaning of sortBy options.

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 coverage is 0% across 11 parameters, so the description carries the burden; it does map several filters (price, registrar, availability) and the 1-or-20 name batch limit. However, it never explains the tlds parameter, the limit default/cap, the sortBy enum values, or how 'name' and 'names' interact, leaving roughly half the parameters undocumented anywhere.

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 and resource ('Search one name or up to 20 names across TLDs') and adds concrete scope (batch pricing, optional availability/price/registrar filters). It is clear without opening the schema, but it never names a sibling such as compare_tlds or check_domain to disambiguate which search tool to pick.

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 explains what the call returns and notes one excluded capability (popularity sorting), but gives no explicit guidance on when to choose this over compare_tlds, check_domain, or cheapest_registrar. Usage context is only implied by the feature list.

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