# get_concept

Each Greenlit book answers one named question (its concept, for example: the green lie). Returns the concept's question, short answer, and full explanation with its book. If the slug is unknown, returns the list of all concept slugs.

Agent View of the PolicyLayer registry record for `get_concept`. HTML page: https://policylayer.com/tools/com-greenlitbooks-catalog/get-concept

## Facts

- Tool: `get_concept`
- Server: Greenlit Books (`https://greenlitbooks.com/api/mcp`) — https://policylayer.com/tools/com-greenlitbooks-catalog.md
- Homepage: https://github.com/greenlitbooks/mcp
- Risk category: Read (Low risk)
- Registry record: grade C, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 1 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `slug` | string | yes | The concept slug, e.g. the-green-lie. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "get_concept",
    "arguments": {
      "slug": "<slug>"
    }
  }
}
```

## Why get_concept is rated Low

Even though get_concept only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

## Use case

AI agents call get_concept to retrieve information from Greenlit Books without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Greenlit Books:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_concept": {}
  }
}
```

## Other tools on Greenlit Books (4)

- `find_books_for_topic` — Read — https://policylayer.com/tools/com-greenlitbooks-catalog/find-books-for-topic.md
- `get_book` — Read — https://policylayer.com/tools/com-greenlitbooks-catalog/get-book.md
- `get_reading_path` — Read — https://policylayer.com/tools/com-greenlitbooks-catalog/get-reading-path.md
- `search_greenlit_books` — Read — https://policylayer.com/tools/com-greenlitbooks-catalog/search-greenlit-books.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-greenlitbooks-catalog · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-greenlitbooks-catalog