eSIM-Global.VIP eSIM Catalog

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds only that the response includes data, validity, network, top-up support, transparency, reviews and a link, which is largely restated by the output schema rather than adding behavioral context such as rate limits or freshness.

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 that leads with the action and resource, then lists the payload. Every clause carries information and there is no filler.

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 a full output schema and annotations covering safety, the description only needs to identify the resource and lookup key, which it does. It is essentially complete, though a brief pointer to the search-to-details workflow would close the remaining 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 100%, so both parameters (including language and its effect on the link's language/currency) are already fully documented. The description mentions only 'by product id' and adds no syntax, format, or constraint detail beyond the schema, which is the baseline 3 case.

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 ('Full details for one eSIM-Global.VIP plan') and the key it is addressed by ('by product id'), plus an enumeration of the fields returned. This implicitly separates it from the list-oriented search_esim_plans, but it never names that sibling, 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?

Usage is only implied: 'Full details ... by product id' suggests it is the follow-up call once an id is known, contrasting with the summary results of search_esim_plans. There is no explicit when-to-use statement and no stated conditions or exclusions, so it is minimal viable 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 declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description usefully adds that results are sorted by eSIM-Global.VIP Data Rating and that prices and a direct link are included, but it says nothing about rate limits, caching, or whether the destination lookup is exhaustive.

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?

Three short sentences, front-loaded with what the tool does, then what it returns, then when to use it. No filler, and every sentence 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?

With annotations covering safety, a fully documented schema, and an output schema handling return values, the description is close to complete. The minor gap is that it does not route the agent among the three sibling tools, and it partially duplicates output-schema territory by describing the result contents.

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 all four parameters (including the city-to-country mapping rule for destination and the currency/language derivation) are already documented in the schema. The description only restates the destination as "country or region" and adds no new meaning, 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 a specific verb (Find) and resource (eSIM plans) scoped to a destination, and adds the return shape (best-value plans with prices and a link). It does not explicitly distinguish itself from the siblings get_plan_details or start_checkout, so an agent must infer the boundary between searching, inspecting, and purchasing.

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 when a user wants mobile data abroad" gives a clear triggering context for the agent. However, it names no alternatives and states no exclusions, so the agent gets no help deciding when to jump to get_plan_details or start_checkout instead.

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/openWorldHint, and the description adds genuinely useful behavior: the returned buy_url is where the customer taps Buy now, payment supports card/Apple Pay/Google Pay plus an optional discount code, no account is required, and the eSIM is emailed after payment. It does not restate the annotations, and the 'no in-chat order tracking' caveat sets accurate expectations about what the tool does not do.

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?

Three tight sentences, front-loaded with the handoff action, then the return value, then the post-payment behavior. No filler and 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?

With an output schema present, return values need not be described, yet it usefully summarizes them; the pre-payment and post-payment expectations are covered. The only real gap is that it never says where product_id comes from, which matters for a single-required-param handoff tool.

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 both parameters are already documented, including that language drives the payment page language/currency. The description adds only 'buy one plan' context for product_id and says nothing about the language parameter, so 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?

Specific verb and resource: it hands the customer off to the shop to buy one plan and returns a buy_url, a plan name, and a price. The purchase/handoff framing is clearly distinct from get_plan_details and search_esim_plans, though the siblings are never 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 implied by 'to buy one plan' and the note that there is no in-chat order tracking, which tells the agent this ends the in-chat flow. However, it never states when this should be called versus the sibling tools, nor that product_id must come from a prior search/details call.

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