Castling MCP and CLI

Castling in your assistant or terminal

Connect a compatible assistant over MCP, or use the CLI in a terminal or coding agent. Both use your Castling account and the same filing-backed warehouse. Pull KPIs and full statements, inspect reported segment composition, screen or compare companies, look up an issuer, browse filing metadata and material Form 8-Ks, search company summaries for context, and reach further back in history on paid plans when the data is available.

MCP server URL

https://mcp.castlingfinancial.com/mcp
Connect in ClaudeConnect in GrokConnect in ChatGPTInstall the CLI

Choose your assistant

Each setup takes a minute. OAuth uses your Castling suite account. CLI install is further down this page.

Claude

Add Castling as a custom MCP connector, authenticate once, then ask equity research questions in chat.

  1. Open Claude (Web).
  2. Go to Customize → Connectors → Add custom connector.
  3. Name it “Castling Financial” and paste the MCP URL below.
  4. Click Connect, sign in to Castling, and approve access.
  5. Start a chat and ask a fundamentals question.
Open Claude connectors

Grok

Add Castling as a custom MCP connector, authenticate once, then ask equity research questions in chat.

  1. Open Grok (Web).
  2. Go to Connectors → New Connector → Custom.
  3. Name it “Castling Financial” and paste the MCP URL below.
  4. Connect, sign in to Castling, and approve access.
  5. Start a chat and ask a fundamentals question.
Open Grok connectors

ChatGPT

Add Castling as a custom MCP connector, authenticate once, then ask equity research questions in chat.

  1. Open ChatGPT (Web).
  2. Go to Settings → Connectors (or your workspace’s custom connector flow).
  3. Name it “Castling Financial” and paste the MCP URL below.
  4. Connect, sign in to Castling, and approve access.
  5. Start a chat and enable the Castling connector.
Open ChatGPT connectors

CLI for coding agents

Install once, then Cursor, Claude Code, and other terminal agents call castling to query the same filing-backed warehouse from a terminal.

CLI calls use the same monthly quota as MCP.

  1. Create a Castling account on the dashboard. CLI login does not create users.
  2. Requires Node.js 22 or newer. Install onto your PATH: npm i -g castling-financial. Or install with Bun: bun add -g castling-financial
  3. Sign in: castling login
  4. Give your agent the skill below after signing in yourself in a terminal.
npm i -g castling-financial
bun add -g castling-financial
castling login
castling script company_kpis --query MSFT --years 2023,2024

MCP and CLI share one allowance. Avoid repeating the same request through both.

Agent skill

# Castling CLI

HTTP client of POST https://api.castlingfinancial.com/v1/call.
Package: castling-financial. Command: castling.
Sign up on the dashboard first. Login does not create accounts.
Do not install any other package name. Do not print tokens.

## Install (once)

Requires Node.js 22 or newer. Install with npm:
npm i -g castling-financial

Bun package manager (Node.js is still required):
bun add -g castling-financial

castling login

Agents: ask the user to run login in their own terminal, then run data commands.

## Prefer one-shot scripts

castling script company_kpis --query MSFT --years 2023,2024

Also: script compare | screen | latest_8k.
CLI and MCP requests share the same monthly quota.

## Exit codes

0 success · 1 usage · 2 auth · 3 history/quota · 4 rate limit · 5 network/server · 130 cancelled

Help is plain text. Success JSON is on stdout; error JSON is on stderr. null stays null.

Tools you get

Five read-only tools, the same surface Castle AI, MCP, and the CLI use, over Castling's equity research warehouse.

  • companyLook up a company by ticker or name, check which data snapshot you are reading, or explain coverage gaps.
  • fundamentalsPull filing-backed KPIs, XBRL line items, full statements, segment axes/series/composition, universe screens, and multi-company compares.
  • filingsForm 10-K, 20-F, and 40-F metadata, plus material Form 8-K and 8-K/A lists and document text.
  • searchSearch company summaries and data-quality notes for context. Not a source of KPI numbers.
  • scriptOne-call playbooks: company_kpis, compare, screen, and latest_8k (resolve + data pull bundled). Counts as one tool call.

Account and suite tiers

MCP uses a one-time OAuth sign-in. The CLI uses dashboard signup, then castling login. History depth and monthly call caps follow your suite tier. MCP and CLI share that cap.

Free

MCP/CLI: recent four fiscal years

50 MCP/CLI calls / month

Standard

MCP/CLI: history back to 2009*

500 MCP/CLI calls / month

Pro

MCP/CLI: history back to 2009*

2,000 MCP/CLI calls / month

Ultra

MCP/CLI: history back to 2009*

10,000 MCP/CLI calls / month

* Paid history goes back to 2009 when available. Not every company has filings that far.

Sign in during the connector OAuth flow. Consent is handled at castlingfinancial.com/oauth/consent.

Try asking

After connecting, prompts like these exercise real Castling tools.

  • “What was Apple's revenue, net income, and free cash flow in 2023?”

  • “Make a line graph of Microsoft revenue and operating cash flow for all years.”

  • “Show Microsoft business segment revenue composition for the latest fiscal year.”

  • “Make a graph comparing Microsoft and Google net income for 2022 to 2024.”

  • “Screen for the top 25 USD companies by free cash flow in the latest annual year.”

  • “List NVIDIA recent Form 8-K filings and explain the latest documents.”

FAQ

What is an MCP?
Model Context Protocol. It lets an AI assistant call Castling tools instead of you pasting filings into chat. Claude, Grok, and ChatGPT are common clients.
Do I need to write code?
Not for MCP. Any AI with an MCP connector can use Castling. Exact menus vary by client, plan, and workspace settings — Claude and ChatGPT are common examples with steps above. The CLI is for assistants that can run a terminal.
What is the MCP URL?
https://mcp.castlingfinancial.com/mcp
How do I install the CLI?
Sign up on the dashboard. With Node.js 22 or newer, install using npm i -g castling-financial. Bun can also install it: bun add -g castling-financial. Then run castling login. The package is castling-financial; the command is castling.
Do I need a Castling account?
Yes. MCP is OAuth-protected. The CLI uses the same account via email login. Sign up on the dashboard first.
Does the CLI use a separate quota?
No. CLI and MCP share the same monthly programmatic call cap and history depth.
Does Castling give investment advice?
No. Castling retrieves and structures public company filing data. It does not provide brokerage, custody, or personalized investment recommendations. See the disclaimer.
Can I use other MCP clients?
Any client that supports remote MCP over HTTP with OAuth should work with the same URL, subject to that client's auth and transport support.

Ready to research inside your assistant?

Connect over MCP, or install the CLI, then ask for equity research data without pasting statements into chat.

Connect to ClaudeConnect to GrokConnect to ChatGPTInstall the CLI