re-ios

check_encryption

Check if a running iOS app uses FairPlay DRM encryption by reading the cryptid field from Mach-O headers of loaded modules.

Instructions

Check if an app is encrypted (FairPlay DRM) by reading cryptid at runtime.

Attaches to the running app and reads the cryptid field from Mach-O headers of all loaded modules.

Args: bundle_id: Bundle identifier of the target app

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": {
      "bundle_id": "<bundle_id>"
    },
    "name": "check_encryption"
  }
}

Input Schema

Name	Required	Description	Default
`bundle_id`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.1Jul 9, 2026

TDQS

B3.2/5.0

Behavior3/5

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

No annotations are provided, so the description carries the full burden. It discloses that the tool attaches to a running app and reads Mach-O headers, implying process injection and potential side effects. However, it does not mention whether the app is killed or resumed, or if special permissions (jailbreak, developer mode) are needed.

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 short, with the first sentence stating the purpose and the second adding technical detail. It is well-structured but could be more concise by avoiding repetition (e.g., 'Attaches to the running app' is implied by 'at runtime').

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

Completeness2/5

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

Given the tool's complexity (runtime process attachment, reading headers), the description lacks important details: it does not specify return value (boolean?), side effects (app state after check), or prerequisites. Since there is no output schema, the return type should be described. The description is incomplete for an agent to fully understand the tool's behavior.

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?

The input schema has one required parameter (bundle_id) with only a title. The description adds meaning by specifying 'Bundle identifier of the target app', clarifying the expected format. With 0% schema description coverage, the description effectively compensates.

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

Purpose4/5

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

The description clearly states the tool checks if an app is encrypted using FairPlay DRM by reading cryptid at runtime. The verb 'check' and resource 'app encryption' are specific. However, it does not explicitly distinguish from siblings like 'check_macho_encryption' or 'dynamic_check_cryptid', which may have overlapping purposes.

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

Usage Guidelines2/5

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

No guidance is provided on when to use this tool versus alternatives. There is no mention of prerequisites (e.g., app must be running), or when not to use it (e.g., if the app is not running or if static analysis is desired).

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