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mcp-signal

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read_messages

Read-onlyIdempotent

Retrieve messages from a specified Signal chat, including sender, date, body, reactions, and attachments. Read-only and requires exact chat name.

Instructions

Read messages from a single Signal chat, returned newest-first.

Each message includes sender, date, body text, reactions, and attachment metadata. Read-only with no side effects. Requires an exact chat name from list_chats. Use search_messages instead to find messages by keyword across chats.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
afterNoISO 8601 datetime; only return messages sent after this time, e.g. '2025-01-15T00:00:00'.
limitNoMaximum number of messages to return, between 1 and 200. Defaults to 20.
beforeNoISO 8601 datetime; only return messages sent before this time, e.g. '2025-02-01T00:00:00'.
offsetNoNumber of messages to skip from the most recent, for pagination (0-10000). Defaults to 0.
chat_nameYesExact chat name as returned by list_chats (case-sensitive).

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv0.2.1
    • changedInput schema / properties / limit / description
      Previous value: -"Maximum number of messages to return, between 1 and 200."New value: +"Maximum number of messages to return, between 1 and 200. Defaults to 20."
    • changedInput schema / properties / offset / description
      Previous value: -"Number of messages to skip from the most recent, for pagination (0-10000)."New value: +"Number of messages to skip from the most recent, for pagination (0-10000). Defaults to 0."
  2. Changed5 schema fields changedv0.1.3
    • addedInput schema / properties / after / description
      Added value: +"ISO 8601 datetime; only return messages sent after this time, e.g. '2025-01-15T00:00:00'."
    • addedInput schema / properties / before / description
      Added value: +"ISO 8601 datetime; only return messages sent before this time, e.g. '2025-02-01T00:00:00'."
    • addedInput schema / properties / chat_name / description
      Added value: +"Exact chat name as returned by list_chats (case-sensitive)."
    • addedInput schema / properties / limit / description
      Added value: +"Maximum number of messages to return, between 1 and 200."
    • addedInput schema / properties / offset / description
      Added value: +"Number of messages to skip from the most recent, for pagination (0-10000)."
  3. First observedv0.1.2

TDQS

A4.5/5.0
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 the description's 'Read-only with no side effects' mostly reinforces known safety. It adds useful non-annotation behavior: results are newest-first and each message includes reactions and attachment metadata. Auth needs, rate limits, and pagination behavior are not described.

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 front-loaded with the core action and ordering, then covers return contents, safety, prerequisite, and alternative routing in four tight sentences. No sentence is wasted or redundant enough to impede scanning.

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?

Given the output schema exists, annotations cover safety and idempotency, and schema coverage is complete, the description supplies exactly the missing contextual pieces: scope, ordering, required input provenance, and sibling routing. An agent has enough information to select and invoke the tool correctly without needing return-value details in prose.

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 schema already fully documents all five parameters, including datetime formats, limit range, and pagination offset. The description adds little beyond restating that chat_name must be exact and come from list_chats, which the schema also states.

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 ('Read messages from a single Signal chat'), specifies the order ('newest-first'), and names the sibling alternative search_messages. An agent can distinguish this tool from list_chats, search_messages, chat_activity, and send_message without opening the 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?

It explicitly states the prerequisite ('Requires an exact chat name from list_chats') and gives a clear alternative condition ('Use search_messages instead to find messages by keyword across chats'). This tells the agent when to use this tool versus a sibling that could otherwise seem overlapping.

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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