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Signal MCP

by googlarz
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

edit_message

Fix typos or update information in a Signal message you already sent by replacing its text, which recipients see with an '(edited)' label. Requires the original timestamp and only works on your own messages.

Instructions

Edit the text of a previously sent message. Sends the edit via signal-cli to all original recipients; they see the updated text inline with an '(edited)' label. Only the message text can be modified — attachments, quoted replies, and reactions are immutable. The edit must reference the exact timestamp of the original message as returned by send_message or get_conversation. Edits can only be made to messages you sent; editing someone else's message returns an error. There is no enforced time limit, but Signal clients may ignore edits on very old messages. Provide recipient for a DM edit or group_id for a group edit; exactly one is required. Use when correcting a typo or updating information in a message you already sent. Do NOT use to change who a message was sent to — send a new message instead.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
messageYesNew message text to replace the original
group_idNoGroup ID for a group message edit
recipientNoPhone number for a DM message edit
target_timestampYesTimestamp of the message to edit (from get_conversation or send_message response)

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed4 schema fields changedv0.1.2
    • changedInput schema / properties / group_id / description
      Previous value: -"Group ID for a group message"New value: +"Group ID for a group message edit"
    • changedInput schema / properties / message / description
      Previous value: -"New message text"New value: +"New message text to replace the original"
    • changedInput schema / properties / recipient / description
      Previous value: -"Phone number for a DM message"New value: +"Phone number for a DM message edit"
    • changedInput schema / properties / target_timestamp / description
      Previous value: -"Timestamp of the message to edit"New value: +"Timestamp of the message to edit (from get_conversation or send_message response)"
  2. First observedv0.1.0

TDQS

A4.8/5.0
Behavior5/5

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

Discloses editing behavior: sends via signal-cli, recipients see '(edited)' label, only text modifiable, must reference exact timestamp, only own messages, no time limit but Signal may ignore old edits. With no annotations, description fully covers behavioral traits.

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?

Description is concise and front-loaded: first sentence states core purpose. Subsequent sentences add necessary constraints without redundancy. Every sentence adds value.

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?

No output schema, but description covers usage context, constraints, and behavioral details like Signal ignoring old edits. Missing explicit return value info, but overall complete for a mutation tool.

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. Description adds value by explaining target_timestamp must be exact, recipient vs group_id usage, and that exactly one is required. This clarifies parameter semantics beyond schema.

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?

Clearly states the tool edits the text of a previously sent message. Distinguishes from send_message, delete_message, and other siblings by specifying that only text is modifiable, not attachments or other elements.

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?

Explicitly says when to use: 'Use when correcting a typo or updating information.' Also states when not to use: 'Do NOT use to change who a message was sent to — send a new message instead.' Provides context on editing only own messages and requiring exact timestamp.

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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