# Screwtape.ai MCP server > Check agent work and invoices before payment, with pass/fail/retry verdicts, duplicate invoice detection and signed receipts. - Listing: https://mcp.tc/i/screwtape-ai - Connect: use the server's own URL `https://screwtape.ai/mcp` (sign-in optional); clients connect to it directly. The listing link is a page, not an MCP endpoint. - Type: remote (Streamable HTTP) - Auth: optional (works without sign-in) - Category: [Finance & Payments](https://mcp.tc/c/finance-payments) - Vendor: Screwtape.ai - Homepage: ## About Screwtape.ai is an independent check on AI agent output. It judges a single draft answer against supplied evidence, scores agreement across 2 to 16 answers to flag false consensus, and checks invoices for duplicates before an agent pays them. Successful results can include an Ed25519 signed receipt, and a receipt can be published as a verification badge. It runs as a hosted streamable HTTP endpoint at https://screwtape.ai/mcp. Calls use a Bearer API key (a free key allows 100 calls per UTC day) or a per-call payment of $0.005 USDC on Base or Solana via x402. Judged content is not stored unless retain is set to true. ## What it can do - Get a pass, fail or retry verdict on one agent output against evidence - Check an invoice for duplicates before an agent pays it - Score 2 to 16 answers for false consensus - Create a free API key through a proof-of-work signup - Get payment requirements for prepaid call packs - Publish a signed receipt as a public verified badge ## Tools (9) - `budget_ledger`: Budget Ledger: atomically reserves reported USD spend across a run and its sub-agents. - `action_receipt`: Action Receipts: Ed25519-signed, hash-chained attestation of an agent-reported action and status; not evidence the action happened or a legal compliance certification. - `payment_check`: Payment check: is this seller safe to pay, checked at the moment the agent pays. (read-only) - `judge`: Return a pass, fail or retry verdict on one agent output, checked against supplied evidence. (read-only) - `check_duplicate_invoice`: Judge an invoice and compare it with earlier recorded invoices to report duplicate status. - `consensus`: Score agreement across 2 to 16 answers and flag copied or thin consensus. (read-only) - `get_api_key`: Create a free API key (100 calls per UTC day) using a SHA-256 proof of work. - `publish_receipt`: Publish one owned signed receipt as a public Screwtape Verified badge page. - `try_check`: See what a spend check returns before you have a key. (read-only) ## Example prompts - "Check this invoice for duplicates before you pay it." - "Judge my draft answer against this evidence and tell me if it passes." - "Run a consensus check on these five agent answers." - "Publish the receipt from the last verdict as a badge." ## Install ### Claude Code 1. Run this in a terminal, in your project folder: ```bash claude mcp add --transport http screwtape-ai https://screwtape.ai/mcp ``` 2. Start Claude Code and type `/mcp`. **screwtape-ai** should show as connected. To sign in for more access, pick it and choose **Authenticate**. Add `--scope user` to make it available in every project, not just this one. Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ### Claude Desktop 1. Open **Customize → Connectors**, click **+ Add**, then **Add custom connector**. 2. Name it **Screwtape.ai** and paste this URL: ```url https://screwtape.ai/mcp ``` 3. Click **Add**, then **Connect**. Signing in to Screwtape.ai is optional. Claude Desktop’s JSON config file only starts local servers. Remote servers go through Connectors, and connectors you add on claude.ai show up here too. ### claude.ai 1. Open the connector form on claude.ai. This button fills in the name and URL for you: [Add to claude.ai]() (opens connector settings) 2. Check that the URL reads `https://screwtape.ai/mcp` and click **Add**. 3. Click **Connect**. Signing in to Screwtape.ai is optional. Free plans allow one custom connector. On Team and Enterprise plans an owner adds it under **Organization settings → Connectors**. ### ChatGPT 1. On chatgpt.com, go to **Plugins**, select **+**, then **Add custom MCP server**. 2. Enter a name for the server. 3. Under **Connection**, paste `https://screwtape.ai/mcp` as the server URL, then for authentication choose **No authentication**, or **OAuth** to sign in to Screwtape.ai for more access. 4. Check **I understand and want to continue**, then select **Create as a plugin**. Whether you can add a custom MCP server depends on your ChatGPT plan and your workspace permissions (in Business workspaces, admins and owners can). ### Cursor [Add to Cursor]() (opens Cursor) Or add it by hand to `~/.cursor/mcp.json` (all projects) or `.cursor/mcp.json` (this project): `mcp.json`: ```json { "mcpServers": { "screwtape-ai": { "url": "https://screwtape.ai/mcp" } } } ``` Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ### VS Code [Install in VS Code]() (opens VS Code) Or from a terminal: ```bash code --add-mcp '{"name":"screwtape-ai","type":"http","url":"https://screwtape.ai/mcp"}' ``` Or commit it to the repo in `.vscode/mcp.json`: `.vscode/mcp.json`: ```json { "servers": { "screwtape-ai": { "type": "http", "url": "https://screwtape.ai/mcp" } } } ``` Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ### Devin Desktop 1. Add it to `~/.config/devin/mcp_config.json` (macOS and Linux) or `%APPDATA%\devin\mcp_config.json` (Windows): `mcp_config.json`: ```json { "mcpServers": { "screwtape-ai": { "serverUrl": "https://screwtape.ai/mcp" } } } ``` 2. Refresh the MCP server list in Cascade. Devin Desktop is the new name for Windsurf. It reads `serverUrl` (or `url`) for remote servers. Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ### Codex ```bash codex mcp add screwtape-ai --url https://screwtape.ai/mcp ``` Or edit `~/.codex/config.toml` directly: `config.toml`: ```toml [mcp_servers.screwtape-ai] url = "https://screwtape.ai/mcp" ``` Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ### Gemini CLI ```bash gemini mcp add --transport http screwtape-ai https://screwtape.ai/mcp ``` Then, inside Gemini CLI, run `/mcp auth screwtape-ai` to sign in (optional). This adds it to the current project. Add `-s user` to use it everywhere. Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ### Any client Most clients accept this shape. Some name the URL field differently: `serverUrl` in Devin Desktop, `httpUrl` in Gemini CLI’s settings file. ```json { "mcpServers": { "screwtape-ai": { "type": "http", "url": "https://screwtape.ai/mcp" } } } ``` Zed puts servers under `context_servers` in its settings. Cline needs `"type": "streamableHttp"`, or it assumes SSE. Client only starts local servers? Bridge it with `npx -y mcp-remote https://screwtape.ai/mcp`. Works without a key. An API key from Screwtape.ai raises the limits: send it as `Authorization: Bearer `. ## Recent changes - 2026-11-10 05:48 UTC: 1 tool added. Server instructions changed. Source: automatic check. Worth a look: new server instructions. Added: payment\_check. - 2026-11-09 14:50 UTC: New version 1.3.0 (was 1.2.2), reported by the server. Source: automatic check. - 2026-11-09 14:50 UTC: 1 tool changed. Source: automatic check. Changed: action\_receipt. - 2026-11-07 14:47 UTC: New version 1.2.2 (was 1.2.0), reported by the server. Source: automatic check. - 2026-11-07 02:45 UTC: 2 tools added and 3 tools changed. Server instructions changed. Source: automatic check. Worth a look: new server instructions. Added: action\_receipt, budget\_ledger. Changed: check\_duplicate\_invoice, consensus, judge. More on the History tab, with descriptions before and after for the newest entries: https://mcp.tc/i/screwtape-ai#history (Atom feed: https://mcp.tc/i/screwtape-ai/history.xml). It records what mcp.tc's anonymous checks saw, every 3 hours where the tool list can be read without sign-in; it is not a security review. ## Details - Server version: 1.4.0 - MCP protocol version: 2025-06-18 - Last checked: 2026-11-15 (reachable) - Listed: 2026-10-24 - Updated: 2026-11-10 --- Source: https://mcp.tc/i/screwtape-ai (mcp.tc is an independent directory, not affiliated with this server's publisher). Corrections: https://mcp.tc/report