signal-cli-mcp

proposeSignalGroupCreation

Propose creating a new Signal group, specifying a name and members, and await approval in a local GUI before anything is sent.

Instructions

Proposes creating a new Signal group. AWAITS human approval in a local GUI — the call may take several minutes. This is not an error; wait patiently. Nothing is sent without approval.

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": {
      "name": "<name>",
      "members": "<members>"
    },
    "name": "proposeSignalGroupCreation"
  }
}

Input Schema

Name	Required	Description
`name`	Yes	Group name.
`reason`	No	Short rationale for the proposal.
`members`	Yes	Members — each a contact name (exact) or an E.164 phone number.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Aug 6, 2026

TDQS

A4.2/5.0

Behavior4/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals the key non-obvious traits: the call blocks for human approval in a local GUI, may take several minutes, and nothing is sent without approval. This is valuable transparency beyond what the schema provides.

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 three sentences, front-loaded with the core purpose, and the rest of the sentences provide essential behavioral warnings. No fluff or repetition.

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 tool with no output schema and moderate complexity, the description adequately covers the unique context: the approval workflow, the potential long wait, and the safety guarantee. It explains what the agent should expect when invoking the tool.

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?

The schema already covers all parameters with descriptions (name, reason, members including format expectations). The description adds no additional parameter-level detail, so the baseline score of 3 is appropriate given the high schema coverage.

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: 'Proposes creating a new Signal group.' This clearly distinguishes it from sibling tools like proposeSignalMessage and proposeSignalGroupMessage, which focus on messages rather than group creation.

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

Usage Guidelines4/5

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

The description clarifies the context of use by noting that human approval is awaited and that the call may take minutes. It does not explicitly mention when not to use it or name alternatives, but the context is clear enough for the agent to decide when this tool is appropriate.

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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