signal-cli-mcp

proposeSignalGroupMessage

Propose sending a Signal message to a group, then wait for human approval in a local GUI. The message is only sent after explicit consent.

Instructions

Proposes sending a Signal message to a 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": {
      "groupId": "<groupId>",
      "text": "<text>"
    },
    "name": "proposeSignalGroupMessage"
  }
}

Input Schema

Name	Required	Description
`text`	Yes	Message text.
`reason`	No	Short rationale for the proposal.
`groupId`	Yes	Target group: a group name (exact, case-insensitive) or a group id (group.<...>).

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Aug 6, 2026

TDQS

A4.4/5.0

Behavior5/5

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

With no annotations provided, the description carries the full burden. It explicitly discloses the approval requirement, the potential multi-minute wait, that the wait is not an error, and that nothing is sent without approval. This is genuinely helpful and goes beyond what structured data could convey.

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, both essential and front-loaded with the most important warnings (approval, wait time, not an error). There is no redundant or filler content.

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?

The description effectively covers the main contextual challenges for this tool: it is a proposal requiring human approval, may take minutes, and should not be mistaken for an error. It does not explain what happens after approval or the response format, but with simple parameters and no output schema, the key risks are addressed.

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 input schema already provides descriptions for all 3 parameters (100% coverage), so the tool description does not need to repeat them. It adds no extra parameter-specific context beyond what the schema already contains, warranting the baseline score.

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 'Proposes sending' with a clear resource 'Signal message to a group'. This distinguishes it from sibling tools proposeSignalMessage (likely for direct messages) and proposeSignalGroupCreation (creating a group).

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 clearly communicates that the call awaits human approval and may take several minutes, setting proper expectations. It does not explicitly mention alternatives or when not to use the tool, but the scope is clear from the name and description.

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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