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Signal MCP

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Python
Local

list_contacts

Read-onlyIdempotent

Browse, filter, or audit Signal contacts from the local store without a network call. Use search, blocked, or all_recipients to narrow results.

Instructions

List the contacts in signal-cli's local contact store (no network call). Use it to browse or audit contacts; to look up one person's number by name, find_contact is the shorter call. Parameters: search (optional) keeps only contacts whose number, name, given/family name, nickname or username contains it (case-insensitive); all_recipients (default false) also includes people not in your address book, e.g. members of your groups; blocked=true returns only blocked contacts, false only unblocked, omitted all. Returns a list of objects with number (E.164), uuid, name, given_name, family_name, about, blocked, display_name, plus username, nick_name, note, has_avatar, message_expiration_time etc. when set.

Input Schema

NameRequiredDescriptionDefault
searchNoFilter contacts by name or number (case-insensitive substring match)
blockedNotrue = only blocked contacts, false = only unblocked (omit for all)
all_recipientsNoAlso include recipients that are not in your address book (e.g. members of your groups), with their profile names

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv1.40.1
    • addedInput schema / properties / all_recipients
      Added value: +{
+  "default": false,
+  "description": "Also include recipients that are not in your address book (e.g. members of your groups), with their profile names",
+  "type": "boolean"
+}
    • addedInput schema / properties / blocked
      Added value: +{
+  "description": "true = only blocked contacts, false = only unblocked (omit for all)",
+  "type": "boolean"
+}
  2. Changed1 schema field changedv0.1.2
    • changedInput schema / properties / search / description
      Previous value: -"Filter contacts by name or number (case-insensitive substring)"New value: +"Filter contacts by name or number (case-insensitive substring match)"
  3. First observedv0.1.0

TDQS

A4.6/5.0
Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new context: it operates on the local store with 'no network call', which sharpens the openWorld hint into an actionable fact. It does not discuss result size or ordering, which is a minor gap.

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?

Front-loaded with the core purpose and the sibling routing, then parameters, then return shape. Dense and mostly waste-free, though the return-field enumeration runs long as one comma-separated tail.

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

Completeness5/5

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

No output schema exists, and the description compensates by naming the returned fields (number, uuid, name, given_name, blocked, etc.). With 100% parameter coverage plus return shape plus sibling routing, an agent has everything needed to call this correctly.

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?

Schema coverage is 100%, so baseline is 3, but the description goes beyond the schema: the schema says search matches 'name or number' while the description enumerates number, name, given/family name, nickname and username. It also spells out the tri-state blocked semantics and gives a concrete example for all_recipients.

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?

States a specific verb and resource (list contacts in signal-cli's local contact store) and immediately distinguishes itself from the sibling find_contact, which does the narrower single-person lookup. An agent can select between the two without opening either schema.

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

Usage Guidelines5/5

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

Explicit when-to-use ('browse or audit contacts') and names the alternative with the condition that selects it ('to look up one person's number by name, find_contact is the shorter call'). Nothing is left to inference.

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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