Posts a comment on Reddit, replying to an existing and accessible submission (post) or another comment.
AI agents use REDDIT_POST_REDDIT_COMMENT to create or update resources in Reddit — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Reddit environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
text | string | — | The raw Markdown text of the comment to be submitted. |
thing_id | string | — | The ID of the parent post (link) or comment, prefixed with 't3_' for a post (e.g., 't3_10omtdx') or 't1_' for a comment (e.g., 't1_h2g9w8l'). |
Parameters from the server's own tool schema.
This tool creates new user-generated content (a comment) on Reddit, which is reversible (comments can be edited or deleted later, as evidenced by sibling tools delete_comment and edit_comment). It has no destructive permanence, does not execute arbitrary code, and involves no financial transactions. The blast radius is limited to the user's account and the specific thread where the comment is posted.
From the tool's definition Tool description states 'Posts a comment on Reddit' - this is a create/write operation that adds new content to the platform.
Documented attack patterns abuse exactly the kind of access REDDIT_POST_REDDIT_COMMENT gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Reddit, and nothing reaches the server without passing your rules. This is the rule we recommend for REDDIT_POST_REDDIT_COMMENT:
{
"version": "1",
"default": "deny",
"tools": {
"REDDIT_POST_REDDIT_COMMENT": {
"limits": [
{
"counter": "reddit_post_reddit_comment_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}REDDIT_POST_REDDIT_COMMENT stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Posts a comment on Reddit, replying to an existing and accessible submission (post) or another comment. It is categorised as a Write tool in the Reddit MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
REDDIT_POST_REDDIT_COMMENT accepts 2 parameters: text, thing_id. The full parameter table on this page comes from the server's own tool schema.
Register the Reddit MCP server in PolicyLayer and add a rule for REDDIT_POST_REDDIT_COMMENT: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Reddit. Nothing to install.
REDDIT_POST_REDDIT_COMMENT is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the REDDIT_POST_REDDIT_COMMENT rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for REDDIT_POST_REDDIT_COMMENT. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
REDDIT_POST_REDDIT_COMMENT is provided by the Reddit MCP server (reddit-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 26 Reddit tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
26 Reddit tools catalogued and risk-classified — across an index of 42,500+ MCP servers.