Queries active travel eSIM data plans. Refines by destination name, country code, or query keywords (e.g. JP, Japan, Japan 100MB, Europe 10GB, USA 30 Days).
| Name | Required | Description | Default |
|---|---|---|---|
| countryCode | No | Destination name, country code, or search keywords (e.g. Japan, JP, Japan 100MB, Europe 10GB). |
| Name | Required | Description | Default |
|---|---|---|---|
| content | No | ||
| isError | No |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "content": {
+ "items": {
+ "properties": {
+ "text": {
+ "type": "string"
+ },
+ "type": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "type",
+ "text"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "isError": {
+ "type": "boolean"
+ }
+ },
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds that only ACTIVE plans are returned, which is real behavioral context, but says nothing about result limits, ranking, or pagination for a search endpoint.
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, purpose front-loaded before the refinement detail. Every clause carries information the 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?
An output schema exists, so return values need no explanation, and a single optional parameter with full schema coverage leaves little to document. The only omission is what 'active' scoping and result ordering mean in practice.
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% and the single parameter already documents the same example formats ('Japan, JP, Japan 100MB, Europe 10GB'). The description's examples restate rather than extend that, so the baseline 3 applies despite a heavy hint that the value doubles as fuzzy keyword search.
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: 'Queries active travel eSIM data plans.' An agent can see this is a discovery/search tool rather than a purchase or top-up tool. It does not explicitly name the nearest sibling (get_topup_packages) or draw the line between them, keeping it 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 implied: this is the catalog lookup an agent would call when hunting for a plan. However there is no explicit 'use this before purchase_esim_with_wallet' guidance, no statement of when not to use it, and no differentiation from get_topup_packages, which also returns purchasable packages.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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