defineMcpMock

Mock an MCP server from its pulled tool list and a result per tool.

Mock a hosted MCP server from its pulled tools/list and a result per tool. Import it from eve-mocks and default-export it from mocks/<name>.ts.

// mocks/linear.ts
import { defineMcpMock } from "eve-mocks";

export default defineMcpMock({
  url: "https://mcp.linear.app/mcp",
  results: {
    get_issue: (args) => ({ identifier: String(args.id), title: "Checkout fails on retry" }),
    list_teams: () => ({ teams: [{ id: "team_1", name: "Platform" }] }),
  },
});

Parameters

Name
`url`	Production MCP endpoint to intercept. `eve-mocks pull` reads `tools/list` from it.
`state`	Initial state per eve session. Optional. See State.
`results`	One answer per tool. The function receives the call’s arguments and `{ state }`, and returns the JSON the tool answers with.

The mock lists only the tools that have a result, so a read-only agent never sees create_issue unless you add it. Every key must name a tool in the pulled schema; a typo fails before the agent starts. Names, descriptions, and input schemas come from that file, so the model reads the same text as in production.

The file name is the mock’s name in list and in the run summary. The MCP transport is stateless: Constraints. How the file fits the run: Mocks.