Siima eSIM

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

With no annotations, the description carries full burden and does so excellently. It discloses multiple behavioral traits: the link is hosted on siima.online (not a Stripe redirect), post-payment delivery of QR code/activation within a minute, no account/signup required, and how the optional email changes the flow. This goes far beyond schema info.

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?

The description is four sentences, front-loads the primary purpose, and each sentence serves a distinct function: purpose, user action, optional parameter behavior, and post-payment outcome. No redundancy or 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?

The tool has no output schema, so the description must explain return values. It mentions 'the returned url' but does not specify the exact return structure. It compensates with rich process details (payment flow, delivery, no account requirement). Slightly more return-format precision would make it a 5.

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% for all parameters, so the baseline is 3. The description adds extra meaning for the email parameter by explaining the behavioral difference between providing and omitting it ('so the link goes straight to the payment page; otherwise the page collects it first'). This added insight justifies a 4.

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 opens with 'Create a secure payment link on siima.online for a Siima eSIM plan', a specific verb+resource statement. It distinguishes the tool from siblings by focusing on generating a payment link rather than searching/listing/retrieving plan data, and explicitly contrasts with a Stripe-hosted redirect.

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 clear context: 'Give the returned url to the user to complete payment' and explains the optional email behavior. However, it does not explicitly name alternatives or state when not to use the tool, so it lacks exclusionary 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?

No annotations provided, so description carries full burden. It implies read-only behavior ('fetch') and mentions no destructive actions. However, it does not disclose what happens on missing plan_id or rate limits. Still adequate for a simple fetch 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, no filler. First sentence states core purpose; second sentence provides crucial workflow. Front-loaded and efficient.

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?

Description covers purpose and usage flow well. However, without an output schema, it does not hint at the structure of returned details (e.g., fields like price, coverage). For a simple fetch tool, nearly complete but missing output shape.

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% with descriptions for both parameters. Description adds context by linking plan_id to search_esim_plans and notes currency default. This extra guidance justifies a score above baseline 3.

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?

Clearly states 'Fetch full details of a single Siima eSIM plan by its id', using a specific verb and resource. Distinguishes from siblings by referencing search_esim_plans for the id and create_checkout_link for purchase.

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?

Explicitly tells when to use (after search, to get full details) and gives a complete workflow: call create_checkout_link with plan id, provide URL to user, and explains automatic email delivery after payment. Guides agent on tool selection versus siblings.

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 no annotations, the description carries the full burden. It discloses that counts and prices are limited to country plans for comparability, and notes that many more countries are reachable via multi-country plans, which is a meaningful scoping constraint. It doesn't mention pagination or ordering, but for a simple list tool, this is adequately transparent.

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, front-loaded with the primary purpose and followed by a necessary scope caveat. No wasted words; every clause adds value.

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?

Given no output schema, the description does a good job indicating what the response contains (countries, counts, prices) and the ISO code format. It also explains the scope limitation clearly. Minor gaps exist around ordering and exact response shape, but for a low-complexity list tool this is sufficiently 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?

The schema already fully documents the currency parameter, including enum values, default, and description. The tool description adds no additional semantic detail about the parameter, but schema coverage is 100%, so the baseline of 3 is appropriate.

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 clearly states the tool lists countries with single-country eSIM plans, including plan counts and cheapest total price. It specifies the ISO 3166-1 alpha-2 format for country codes and distinguishes itself from sibling list_regions by explicitly noting the scope limitation to single-country plans.

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 explicitly explains when to use this tool (for single-country plans) and directs users to list_regions for multi-country plans. This provides clear when-to-use vs. alternative guidance, satisfying the highest bar for this dimension.

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 no annotations, the description carries the full burden. It discloses the read-only nature via 'List' and specifies the output contents (countries, plan count, cheapest total price). It doesn't describe side effects or errors, but for a simple listing tool, this is adequate and not misleading.

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?

The description is exactly three sentences: a purpose statement, a usage instruction, and an alternative recommendation. Every sentence adds value with no fluff, and the most critical information is front-loaded.

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 only two optional parameters and no output schema, the description fully covers what it does, what it returns, how to use it in a workflow, and when to use an alternative. Nothing essential 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?

The schema already provides 100% description coverage for both parameters (country and currency), including formats and defaults. The description does not add additional parameter-specific details beyond the schema, so the baseline of 3 is appropriate.

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 clearly states the tool lists every multi-country coverage area with specific details (countries covered, plan count, cheapest price). It uses the specific verb 'List' and explicitly distinguishes from list_destinations by addressing multi-country vs single-country trips.

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?

Explicit usage guidance is provided: 'Use this for a trip crossing several countries' and includes the workflow of passing the coverage name to search_esim_plans. It also names the alternative for single-country trips, making when-to-use unmistakable.

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 no annotations, the description carries the full burden and excels: it reveals that a country filter matches plans of any coverage type, that returned prices are final checkout amounts including all fees, and that eSIM delivery is automatic via email without an account. These behaviors are not evident from the schema or name.

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?

The description is a dense but coherent paragraph; each sentence adds value, covering filters, coverage-type nuances, price behavior, and the purchase flow. It is not verbose, though a slightly more bulleted structure could improve scannability without losing content.

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 complex tool with 9 parameters, no annotations, and no output schema, the description is remarkably complete: it explains filter behaviors, gives selection advice, clarifies pricing, and maps the next step to create_checkout_link. It does not describe the response structure or pagination, but these are less critical for correct 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?

The schema already covers all 9 parameters, but the description enriches meaning by explaining the three coverage types, the inclusive country-filter behavior, and the price semantics ('final amount the customer pays at checkout'). This goes beyond the schema's field descriptions, though not every parameter receives equal attention.

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 clearly states the tool's purpose: 'Search prepaid travel eSIM data plans' with a specific verb and resource. It enumerates the available filters and even names the follow-up tool create_checkout_link, distinguishing it from sibling tools like get_esim_plan or list_regions.

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 offers explicit usage guidance: 'For a trip through several countries, filter coverage_type="regional" or "global"...' and 'for a single-country trip a "country" plan is usually cheapest.' It also tells the agent what to do after finding a plan ('To buy: call create_checkout_link'), providing a clear decision path.

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