Adds a comment to an existing Linear issue. Supports markdown formatting in the comment body. Can optionally specify a custom user name and avatar for the comment. Returns the created comment
AI agents use linear_add_comment to create or update resources in Linear MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Linear MCP Server environment.
This tool creates new comment data within Linear issues, which is a reversible write operation. It modifies issue state by appending comments but does not delete, destroy, or execute arbitrary code. The severity is medium because malicious comments could spam, harass, or spread misinformation across a team's issue tracker, but the blast radius is limited to comment data rather than destructive or financial impact.
From the tool's definition Tool description states 'Adds a comment to an existing Linear issue' and 'Returns the created comment', indicating creation of new data (comments) in the Linear system.
Documented attack patterns abuse exactly the kind of access linear_add_comment gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Linear MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for linear_add_comment:
{
"version": "1",
"default": "deny",
"tools": {
"linear_add_comment": {
"limits": [
{
"counter": "linear_add_comment_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}linear_add_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.
Free to start. No card required.
Adds a comment to an existing Linear issue. Supports markdown formatting in the comment body. Can optionally specify a custom user name and avatar for the comment. Returns the created comment. It is categorised as a Write tool in the Linear MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Linear MCP Server MCP server in PolicyLayer and add a rule for linear_add_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 Linear MCP Server. Nothing to install.
linear_add_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 linear_add_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 linear_add_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.
linear_add_comment is provided by the Linear MCP Server MCP server (jerhadf/linear-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Linear MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
5 Linear MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.