viber-mcp

send_message

Send a text message to a Viber user via bot. Provide receiver user ID and message text, with optional sender details.

Instructions

Send a text message to a Viber user

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": {
      "receiver": "<receiver>",
      "text": "<text>"
    },
    "name": "send_message"
  }
}

Input Schema

Name	Required	Description
`receiver`	Yes	Viber user ID of the receiver (obtained from a previous incoming event)
`text`	Yes	Message text, up to 7000 characters
`sender_name`	No	Display name override (≤28 chars). Defaults to VIBER_SENDER_NAME env var.
`sender_avatar`	No	Avatar URL override. Defaults to VIBER_SENDER_AVATAR env var.
`tracking_data`	No	Opaque data echoed back in delivery callbacks

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 26, 2026

TDQS

B3.1/5.0

Behavior2/5

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 only says 'send a text message' without disclosing behavioral traits like API call behavior, error handling, or rate limits.

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 a single, concise sentence that delivers the core purpose with no wasted words, though it could include more context without sacrificing brevity.

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 no annotations and no output schema, the description is too sparse. It omits important context such as expected return values, error conditions, or integration requirements.

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%, so the description does not need to add parameter details. It adds no extra meaning beyond the tool's purpose, which is acceptable for high-coverage schemas.

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 action ('send a text message') and target ('to a Viber user'), which effectively distinguishes it from sibling tools like send_picture or send_video.

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 on when to use this tool vs alternatives (e.g., other send_* tools) or prerequisites (e.g., receiver must be a valid Viber user ID from a prior event).

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

Deploy Server