sub_issue_write
Add a sub-issue to a parent issue in a GitHub repository.
This record as markdown: /tools/github/sub-issue-write.md
What sub_issue_write does on GitHub
AI agents use sub_issue_write to create or update resources in GitHub, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your GitHub environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
repo | string | — | Repository name |
owner | string | — | Repository owner |
method | string | — | The action to perform on a single sub-issue Options are: - 'add' - add a sub-issue to a parent issue in a GitHub repository. - 'remove' - remove a sub-issue fro |
after_id | number | — | The ID of the sub-issue to be prioritized after (either after_id OR before_id should be specified) |
before_id | number | — | The ID of the sub-issue to be prioritized before (either after_id OR before_id should be specified) |
issue_number | number | — | The number of the parent issue |
sub_issue_id | number | — | The ID of the sub-issue to add. ID is not the same as issue number |
replace_parent | boolean | — | When true, replaces the sub-issue's current parent issue. Use with 'add' method only. |
Parameters from the server's own tool schema.
Why sub_issue_write is rated Medium
This tool creates or modifies data (adding a sub-issue link) in a reversible manner. It does not delete data (not Destructive), does not execute arbitrary code (not Execute), involves no financial transactions (not Financial), and is not a read-only operation (not Read).
From the tool's definition Tool name contains 'write' and description states 'Add a sub-issue', which creates a new data structure (sub-issue) within GitHub's issue tracking system.
Attacks that exploit this kind of access
The rule that runs sub_issue_write safely
PolicyLayer is an MCP gateway: it sits between your AI agents and GitHub, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For sub_issue_write, this is the rule to start with:
sub_issue_write 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.
The button opens the PolicyLayer dashboard: create your workspace, connect GitHub, apply this rule, and every sub_issue_write call is checked against it from then on.
Questions about sub_issue_write
Add a sub-issue to a parent issue in a GitHub repository. It is categorised as a Write tool in the GitHub MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
sub_issue_write accepts 8 parameters: repo, owner, method, after_id, before_id, issue_number, sub_issue_id, replace_parent. The full parameter table on this page comes from the server's own tool schema.
Register the GitHub MCP server in PolicyLayer and add a rule for sub_issue_write: 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 GitHub. Nothing to install.
sub_issue_write 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 sub_issue_write 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 sub_issue_write. 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.
sub_issue_write is provided by the GitHub MCP server (oci:ghcr.io/github/github-mcp-server:1.3.0). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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