Cursor MCP Server Setup: Search Your Documentation From the Editor

Adding documentation search to Cursor takes one configuration file: declare a remote MCP server in `.cursor/mcp.json`, pass an API key in an `Authorization` header, and Cursor's agent can query your documentation and cite its sources mid-task. This guide gives the exact JSON, explains the three tools you get, suggests prompts that behave predictably and lists the usual reasons a server fails to connect.

The problem MCP solves inside Cursor

Cursor indexes your repository well. What it cannot see is the knowledge that sits outside the code: the internal style guide, the integration manual from a supplier, the HMRC notice your invoicing module has to respect. Developers usually bridge that gap by pasting pages into the chat, which is tedious, eats context and goes stale.

Searching documentation through a tool also changes how answers can be checked. Instead of a fluent paragraph you have to trust, the agent receives numbered passages and can quote them back to you, so a reviewer sees where each claim comes from. For a regulated codebase, that audit trail is often worth more than the time saved.

The Model Context Protocol is an open standard for connecting AI clients to external tools. A documentation server exposes search as a tool; Cursor's agent calls it when it needs facts, reads the passages that come back and works from them. Behind the tool sits a retrieval pipeline, which is exactly what RAG as a service provides without you running any infrastructure.

Before you begin: a short checklist

• Cursor, a current release with MCP support.
• A base to query. Browse the catalogue of knowledge bases, or create your own base from your documentation (PDF, Word, text or Markdown; creation is free). Kopik extracts, chunks and indexes the files for hybrid search.
• An API key from your Kopik dashboard, beginning with `kpk_`. The free `list_bases` tool is the only one that works without it.
• Five minutes and permission to add a file to the project.

Writing the .cursor/mcp.json file

At the root of your project, create a `.cursor` directory containing a file called `mcp.json`. Its content is a single object: `{ "mcpServers": { "kopik": { "url": "https://kopik.io/api/mcp", "headers": { "Authorization": "Bearer kpk_…" } } } }`. Replace `kpk_…` with your full key. Save the file, then open Cursor's MCP settings: the server should appear with its tools.

A few details are worth understanding rather than copying blindly:

• The transport is Streamable HTTP and stateless. There is no local process to install or keep running; Cursor simply sends requests to the URL.
• The name `kopik` is yours to choose. It is only a label in Cursor's interface.
• The header is mandatory for paid tools. `Bearer`, one space, then the key.
• A global file also exists. If you want the server in every project, put the same content in the `mcp.json` file of the `.cursor` folder in your home directory.

One project, one base

The default URL opens the entire catalogue, and the agent names a base on each call. For a project tied to a single documentation set, use the base's own URL instead: `https://kopik.io/api/mcp?base=your-base-slug`, copied from the base page. The `base` argument then vanishes from the tools, prompts become shorter and the agent cannot drift to an unrelated base. This works for private bases too, with the owner's key.

The three tools Cursor will see

`maxPriceCents` is a safety cap: if the base costs more than the figure you set, the call is refused and nothing is charged. Questions to your own bases are free within reasonable use (around 200 a day); other bases are billed from prepaid credits at the price their creator set.

Prompts that get consistent results

Cursor's agent chooses when to use a tool, so the clearer the instruction, the more predictable the call. These patterns work well:

1. "Run list_bases with the query 'VAT' and suggest the base best suited to questions on the domestic reverse charge."
2. "Ask the base uk-vat-guide-hmrc when the domestic reverse charge applies to construction services, and quote the passages you used."
3. "Use search_base on our-platform-handbook for 'webhook signature verification', then implement verifySignature in this file and reference the passage numbers in a comment."
4. "Call ask_base on our-platform-handbook with maxPriceCents 0 and summarise how we version public endpoints." (A cap of 0 is fine for your own free bases.)
5. "Before changing this migration, check our-platform-handbook for the rules on renaming database columns."

When the connection fails: troubleshooting

If the agent replies without consulting the server at all, name the tool and the base in the prompt, or pin the server to a single base. For scripted use, JSON-RPC batches are limited to 10 requests.

A note on prompt injection

Any tool that feeds documents into an agent can carry hostile text. Kopik wraps base content in kopik-untrusted tags so the client can treat it as data rather than instructions. Keep Cursor's per-call approval switched on while you get used to the setup, especially in sessions where the agent can also edit files or run terminal commands.

On cost, API and MCP calls are always billed at the base's price per question, from prepaid credits; the free questions offered on the website do not apply to MCP. Your own bases stay free within reasonable use. Before rolling the setup out to a whole team, agree on three things: which bases the project may query, a default `maxPriceCents` written into your team's agent instructions, and who owns the API key. A shared key is convenient, but individual keys make it far easier to revoke access when someone leaves and to see who is spending what.