Ninja MCP

by Khaled-Harthi

Overview Schema Source Related Servers Discussions Admin

TypeScript

Local

Start Ninja OTP Login

ninja_auth_start_login

Start the login process by registering a device session and sending an OTP to the user's mobile number.

Instructions

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": {
      "mobileNumber": "<mobileNumber>"
    },
    "name": "ninja_auth_start_login"
  }
}

Input Schema

Name	Required	Description	Default
`mobileNumber`	Yes	Account phone number, preferably +9665XXXXXXXX.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 15, 2026

TDQS

A3.6/5.0

Behavior3/5

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

With no annotations, the description carries full burden. It discloses that an OTP is sent and a device session is registered, which are key behavioral traits. However, it omits details like whether existing sessions are invalidated, rate limits, or auth requirements. Adequate but not thorough.

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

Conciseness5/5

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

The description is two sentences, each adding value. It is front-loaded with the core action and includes the key consequence (sends OTP). No extra words; highly efficient.

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 simple one-parameter tool with no output schema, the description covers the essential purpose. It could mention the next expected step (verify_otp) or typical response, but it is largely complete given the tool's complexity.

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

Parameters3/5

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

Schema description coverage is 100% (the mobileNumber parameter includes a preferred format). The tool description adds no additional semantic value beyond what the schema already provides, so baseline 3 is appropriate.

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 clearly states the verb (register, start, send) and the resource (device session, phone login, OTP). It distinguishes from siblings like ninja_auth_verify_otp and ninja_auth_status, which handle subsequent steps or status checks.

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, such as prerequisites (e.g., user must not already be logged in) or the typical flow (e.g., call this before verify_otp). The description lacks any usage context.

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