Cypher eSIM

List plans

list_plans

Read-onlyIdempotent

List purchasable plans for a destination, cheapest first. type "data" = data-only eSIM: validity starts on first connection at the destination. type "number" = eSIM with a phone number, calls and SMS: validity starts at installation, so install it just before use; Europe plans give a French +33 number; the UK number plan must be installed only after arrival in the UK. For a country without its own plans, regional and world plans that cover it are returned. Prices are final USD prices; the crypto amount is set at create_order.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "destination": "<destination>"
    },
    "name": "list_plans"
  }
}

Input Schema

Name	Required	Description
`type`	No	"data" (default) or "number" (plan with a phone number)
`destination`	Yes	Destination code from search_destinations, or a country ISO2 code
`include_regional`	No	For a country: also return regional/world plans covering it

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A4.3/5.0

Behavior5/5

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

Annotations already declare a safe, idempotent, read-only, closed-world operation, yet the description adds substantial context beyond them: validity start rules for data vs number plans, install-timing warnings, the French +33 number for Europe, the UK after-arrival constraint, regional fallback behavior, and final USD pricing with crypto set at create_order.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the core purpose and ordering, then layers useful warnings. It runs several dense sentences, but nearly every clause carries decision-relevant information such as install timing and regional fallback.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only list tool with no output schema, the description covers purpose, type semantics, fallback behavior, and pricing. It does not describe the return shape or pagination, which is a minor gap but not critical for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3, but the description meaningfully expands the type parameter beyond its brief schema description by explaining validity start, phone/SMS capability, and regional number formats. It says less about include_regional and destination, so it does not fully saturate all three parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('List purchasable plans for a destination') and adds a distinguishing ordering guarantee ('cheapest first'). An agent can tell this apart from the singular get_plan sibling without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explains how to choose the plan type and references create_order for crypto pricing, which implies an ordering workflow. However, it never explicitly says when to use this tool versus siblings like get_plan or search_destinations, so usage is implied rather than directed.

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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