This record as markdown: /tools/github/update-gist.md
What update_gist does on GitHub
AI agents use update_gist 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 |
|---|---|---|---|
content | string | — | Content for the file |
gist_id | string | — | ID of the gist to update |
filename | string | — | Filename to update or create |
description | string | — | Updated description of the gist |
Parameters from the server's own tool schema.
Why update_gist is rated Medium
This tool modifies existing gist content, which is a reversible Write operation. It does not create new resources (that would be Create/Write at lower severity), delete data (Destructive), or execute arbitrary code. The severity is medium because unauthorized gist updates could affect shared code snippets or documentation, with moderate blast radius depending on gist visibility and usage.
From the tool's definition The tool description explicitly states "Update an existing gist". Updates reversibly modify data without deleting it.
Risk signalsAccepts raw HTML/template content (content) · Accepts file system path (filename)
Attacks that exploit this kind of access
The rule that runs update_gist 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 update_gist, this is the rule to start with:
update_gist 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 update_gist call is checked against it from then on.
Questions about update_gist
Update an existing gist. 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.
update_gist accepts 4 parameters: content, gist_id, filename, description. 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 update_gist: 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.
update_gist 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 update_gist 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 update_gist. 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.
update_gist 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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