Reddit MCP Server

edit_comment

DestructiveIdempotent

Overwrite the text of your own Reddit comment by providing its ID and new content. Requires your account credentials; preserves the post and adds an edited marker. Use idempotently to update replies.

Instructions

Replace the text of one of your own comments. Mutating and idempotent (same text → same result); it overwrites the previous content. Requires REDDIT_USERNAME and REDDIT_PASSWORD, and works only on comments you authored. Adds an "edited" marker. Use reply_to_post to add a new comment, or edit_post for posts. WARNING: rapid edits may trigger spam detection; enable REDDIT_SAFE_MODE for protection.

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": {
      "thing_id": "<thing_id>",
      "new_text": "<new_text>"
    },
    "name": "edit_comment"
  }
}

Input Schema

Name	Required	Description	Default
`new_text`	Yes	Replacement comment text; fully overwrites the current content. Reddit markdown supported.
`thing_id`	Yes	The comment to edit: a full thing id 't1_<id>' or just the base36 comment id '<id>' (the 't1_' prefix is added automatically). Must be a comment you authored.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.5.3Aug 20, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations include destructiveHint=true and idempotentHint=true; the description reinforces and expands on these by stating 'Mutating and idempotent (same text → same result); it overwrites the previous content' and 'Adds an "edited" marker.' It also discloses potential spam detection risk, which is beyond the annotations. No contradiction.

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?

Three sentences, each earning its place: purpose, usage constraints/alternatives, and a warning. Front-loaded with the core action, no redundant phrasing.

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?

For a simple 2-parameter mutating tool with annotations and no output schema, the description covers purpose, side effects (overwrite, edited marker), prerequisites, alternative tools, and risk mitigation. It is fully self-contained for an agent to select and invoke the tool correctly.

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%, with both new_text and thing_id well described in the schema. The tool description adds no new parameter-level detail beyond what is already in the schema (e.g., it repeats 'overwrites' and 'comments you authored' but doesn't add syntax or format details). Baseline 3 is appropriate.

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 opens with 'Replace the text of one of your own comments,' which is a specific verb (replace) and resource (one of your own comments). It clearly distinguishes from sibling tools by explicitly mentioning reply_to_post for new comments and edit_post for posts.

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?

Provides explicit guidance: 'Use reply_to_post to add a new comment, or edit_post for posts' names alternatives. It also states prerequisites ('works only on comments you authored', 'Requires REDDIT_USERNAME and REDDIT_PASSWORD') and a warning about rapid edits with a mitigation (REDDIT_SAFE_MODE).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.