Fiber AI — MCP Server

The Model Context Protocol (MCP) server provides a standardized interface that allows any compatible AI agent to access Fiber AI's data and tools — search companies, enrich contacts, reveal emails, and more — directly from your editor.

For AI agents

If you are a coding agent and need to pick between MCP and the REST API, start with the canonical agent-facing docs on the API:

• Routing index + critical rules: https://api.fiber.ai/llms.txt
• Per-operation markdown: https://api.fiber.ai/ai-docs/<operationId>.md
• Operation index: https://api.fiber.ai/ai-docs/index.md
• MCP walkthrough for LLMs: https://docs.fiber.ai/article/using-mcp-in-llms

Rule of thumb: use MCP when you're acting inside an IDE / chat and each operation is a tool call; use the REST API (via @fiberai/sdk or fiberai) when you're building an autonomous script or a production pipeline.

Servers

Fiber AI offers three remote MCP servers:

Which one should I use? V2 is the fastest path for the most common flows with an API key. V3 is the most ergonomic for broad agent coverage — it exposes every public operation as a direct tool with compact descriptions, authenticated via browser-based SSO login instead of a pasted key. Core keeps the tool count tiny (5) and lets the agent discover endpoints at runtime; it uses the same API-key auth as V2. You can register more than one; the server names (fiber-ai-v2, fiber-ai-v3, fiber-ai-core) stay distinct.

Setup

Smithery

Install via Smithery with a single command:

npx -y @smithery/cli install @fiber-ai/mcp --client cursor

Replace cursor with your client: claude, windsurf, vscode, zed, etc.

Or browse and install from the Smithery web UI at smithery.ai/server/@fiber-ai/mcp.

Cursor

Click the link below to install automatically — paste it into your browser address bar and press Enter:

Install V2:

cursor://anysphere.cursor-deeplink/mcp/install?name=FiberAI-V2&config=eyJ1cmwiOiJodHRwczovL21jcC5maWJlci5haS9tY3AvdjIifQ==

Install Core:

cursor://anysphere.cursor-deeplink/mcp/install?name=FiberAI&config=eyJ1cmwiOiJodHRwczovL21jcC5maWJlci5haS9tY3AifQ==

Or manually: open Cursor Settings → Features → MCP → "+ Add New MCP Server" → Type: HTTP → URL: https://mcp.fiber.ai/mcp/v2

Claude Code

The simplest path passes your key as a header so the agent never sees it in chat:

claude mcp add --transport http fiber-ai-v2 https://mcp.fiber.ai/mcp/v2 \
  --header "x-api-key: $FIBER_API_KEY"

To also add the Core server:

claude mcp add --transport http fiber-ai https://mcp.fiber.ai/mcp \
  --header "x-api-key: $FIBER_API_KEY"

Or, if you prefer to give the key via chat, drop the --header flag and the agent will pass apiKey in the request body when you tell it your key.

Run /mcp inside a Claude Code session to verify the connection.

Claude Desktop

From Claude settings → Connectors, add a new MCP server with the URL https://mcp.fiber.ai/mcp/v2.

Or edit your claude_desktop_config.json:

{
  "mcpServers": {
    "fiber-ai-v2": {
      "url": "https://mcp.fiber.ai/mcp/v2",
      "transport": { "type": "http" },
      "headers": { "x-api-key": "sk_live_..." }
    },
    "fiber-ai": {
      "url": "https://mcp.fiber.ai/mcp",
      "transport": { "type": "http" },
      "headers": { "x-api-key": "sk_live_..." }
    }
  }
}

The headers field is optional - if you omit it, the agent will pass apiKey in the request body when you give it your key in chat.

Codex

codex mcp add fiber-ai --url https://mcp.fiber.ai/mcp/v2

Or add to ~/.codex/config.toml:

[mcp_servers.fiber-ai]
url = "https://mcp.fiber.ai/mcp/v2"
transport = "http"

[mcp_servers.fiber-ai.headers]
x-api-key = "sk_live_..."

The [mcp_servers.fiber-ai.headers] block is optional - drop it and give the key in chat instead.

Visual Studio Code

Press Ctrl/Cmd + P, search for MCP: Add Server, select Command (stdio), and enter:

npx mcp-remote https://mcp.fiber.ai/mcp/v2

Name it FiberAI and activate it via MCP: List Servers.

Or add to .vscode/mcp.json. If your VS Code version supports HTTP MCP natively, prefer the header-based shape:

{
  "mcpServers": {
    "fiber-ai": {
      "type": "http",
      "url": "https://mcp.fiber.ai/mcp/v2",
      "headers": { "x-api-key": "${env:FIBER_API_KEY}" }
    }
  }
}

Older VS Code releases need the stdio wrapper (mcp-remote forwards your FIBER_API_KEY env var as a header):

{
  "mcpServers": {
    "fiber-ai": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.fiber.ai/mcp/v2",
        "--header",
        "x-api-key:${FIBER_API_KEY}"
      ]
    }
  }
}

Windsurf

Press Ctrl/Cmd + , → Cascade → MCP servers → Add custom server:

{
  "mcpServers": {
    "fiber-ai": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.fiber.ai/mcp/v2",
        "--header",
        "x-api-key:${FIBER_API_KEY}"
      ]
    }
  }
}

Zed

Press Cmd + , and add:

{
  "context_servers": {
    "fiber-ai": {
      "source": "custom",
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.fiber.ai/mcp/v2",
        "--header",
        "x-api-key:${FIBER_API_KEY}"
      ],
      "env": { "FIBER_API_KEY": "sk_live_..." }
    }
  }
}

Others

Most MCP-compatible tools can be configured with:

• URL: https://mcp.fiber.ai/mcp/v2
• Transport: HTTP (Streamable HTTP)
• Auth: header x-api-key: <your key> (or Authorization: Bearer <your key>)
• For stdio-only clients: npx -y mcp-remote https://mcp.fiber.ai/mcp/v2 --header x-api-key:$FIBER_API_KEY

Available Tools

V2 Server (/mcp/v2/)

Direct API tools — each Fiber AI endpoint is exposed as an individual tool:

Core Server (/mcp)

Meta tools for dynamic endpoint discovery:

Authentication

V2 and Core require a Fiber AI API key. V3 uses OAuth (Clerk SSO) - the client opens a browser window for login and reuses the session token, no key configuration needed. Get an API key at fiber.ai/app/api.

You can supply your key in any of these three ways - pick whichever your client makes easiest:

Option A - via chat (zero config)

The agent passes the key in the request body as apiKey. Simplest path: paste your key into the agent once and it'll keep using it.

You:    Use sk_live_... as my Fiber API key.
Agent:  [calls api_companySearch with { "apiKey": "sk_live_...", "searchParams": {...} }]

Caveat: the key ends up in chat history. Fine for personal use, not ideal for shared sessions.

Option B - via x-api-key header (recommended for IDEs)

Configure the header once in your MCP client config; the agent never sees the key.

{
  "mcpServers": {
    "fiber-ai-v2": {
      "type": "http",
      "url": "https://mcp.fiber.ai/mcp/v2",
      "headers": { "x-api-key": "sk_live_..." }
    },
    "fiber-ai-core": {
      "type": "http",
      "url": "https://mcp.fiber.ai/mcp",
      "headers": { "x-api-key": "sk_live_..." }
    }
  }
}

Most clients (Claude Code, Cursor, Claude Desktop, Codex, Windsurf, VS Code) accept a headers field on each MCP server. Reference your env var instead of hard-coding:

"headers": { "x-api-key": "${env:FIBER_API_KEY}" }

Option C - via Authorization: Bearer header

Same shape as Option B, but using the standard bearer-token header. Useful if your MCP client only supports Authorization-style auth.

"headers": { "Authorization": "Bearer sk_live_..." }

Resolution order

When more than one is present, the server resolves in this order: body/query apiKey -> x-api-key header -> Authorization: Bearer. The first non-empty value wins.

V3 (OAuth)

V3 ignores all of the above. On first connect, the client opens https://app.fiber.ai for browser-based SSO login; the resulting session token is reused on subsequent calls. No env vars, no headers, no config to write.

Example Usage

Once connected, ask your AI agent:

• "Search for SaaS companies in New York with 50-200 employees"
• "Find the CEO of and get their work email"
• "How many credits do I have left?"
• "Enrich this LinkedIn profile: linkedin.com/in/..."

• TypeScript: npm install @fiberai/sdk — GitHub
• Python: pip install fiberai — GitHub

FAQ

Connection not working? Ensure your editor supports HTTP (Streamable HTTP) MCP transport. If it only supports stdio, use the npx mcp-remote wrapper shown in the VS Code / Windsurf / Zed instructions.

Getting authentication errors? Make sure you're supplying a valid key via one of the three supported paths (body apiKey, x-api-key header, or Authorization: Bearer). See Authentication above. Get a key at fiber.ai/app/api.

Should I put the key in chat or in headers? For personal sessions, chat is fine. For shared sessions, team-config files committed to git, or anywhere chat history might leak, configure the x-api-key header at the MCP client layer so the agent never sees the raw key.

Can I use both servers at the same time? Yes. Many users add both V2 and Core for maximum flexibility.

License

MIT