Get the custom field definitions available in the authenticated Linear workspace
AI agents call linear_getCustomFields to retrieve information from Linear without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metadata about custom field definitions without any side effects. It is a straightforward read operation that queries workspace configuration data. The blast radius of misuse is minimal since it only exposes schema/metadata information that does not expose sensitive user data or enable destructive actions.
From the tool's definition The tool name includes 'get' and the description states it retrieves 'custom field definitions available in the authenticated Linear workspace' with no modification, deletion, or execution implied.
Documented attack patterns abuse exactly the kind of access linear_getCustomFields gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Linear, and nothing reaches the server without passing your rules. This is the rule we recommend for linear_getCustomFields:
{
"version": "1",
"default": "deny",
"tools": {
"linear_getCustomFields": {}
}
}linear_getCustomFields is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Get the custom field definitions available in the authenticated Linear workspace. It is categorised as a Read tool in the Linear MCP Server, which means it retrieves data without modifying state.
Register the Linear MCP server in PolicyLayer and add a rule for linear_getCustomFields: 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. Nothing to install.
linear_getCustomFields is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the linear_getCustomFields 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_getCustomFields. 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_getCustomFields is provided by the Linear MCP server (tacticlaunch/mcp-linear). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 182 Linear tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
182 Linear tools catalogued and risk-classified — across an index of 42,500+ MCP servers.