Senzing Cookbook · Setup & troubleshooting
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Ask your assistant first
Diagnose the problem
Firewall & proxy
Browser tools
Claude Desktop app
Ask your assistant first
Diagnose the problem
Firewall & proxy
Browser tools
Claude Desktop app
Heads-up
assistant UIs change fast, so any exact clicks below (dated August 2026) may look different in your version. The always-current move is to ask your assistant – “how do I add an MCP server?” or “how do I allow a domain for code execution?” – it knows its own current setup.
Ask your assistant first
For almost anything here, the quickest fix is to ask the assistant itself:
Add the MCP
paste the prompt below – or ask “how do I add an MCP server?”
Paste this
Add the Senzing MCP server at https://mcp.senzing.com/mcpAllow downloads
ask the prompt below:
Ask this
How do I allow the domain mcp.senzing.com for your code execution?Something not working? Check these two things
Almost every setup problem is one of two failure modes:
Symptom 1
The assistant can’t see any Senzing tools
→ the connector isn’t added.
Fix: add it in the assistant’s MCP / connector settings using https://mcp.senzing.com/mcp (no authentication), or ask the assistant how. Claude Desktop specifics are below.
Symptom 2
The tools work, but a recipe stalls when it installs Senzing or downloads data
→ the assistant’s code sandbox can’t reach mcp.senzing.com.
You’ll see a 403, a DNS error, or a timeout.
Fix: allow mcp.senzing.com in the assistant’s network / code-execution settings (Claude Desktop specifics below), or ask the assistant how. If it still fails after that, the block is your network (a corporate firewall or proxy) – see the next section.
These are independent: the connector is routed from the assistant’s servers, so it can work even while the sandbox’s downloads are blocked.
Behind a corporate firewall or proxy?
In a managed / corporate environment, downloads can be blocked at two layers – and both have to allow the traffic:
1
Your assistant’s own egress setting (for example, Claude Desktop’s domain allowlist – see below).
2
Your corporate network – a firewall or proxy can block the domain even after the assistant is set up correctly.
So if downloads still fail once you’ve allowed it in the assistant, it’s the network. Ask IT / your network admin to allow outbound HTTPS (port 443) to:
mcp.senzing.com
the MCP server, plus the Senzing SDK / package downloads and workflow resources.
senzing.com
some dataset (CORD) downloads are served from here.
Using an HTTPS proxy? Make sure the assistant’s code-execution environment is pointed at it (e.g. via the HTTPS_PROXY variable) so its downloads route through the proxy rather than getting refused.
Reading the error
403
→
(blocked-by-allowlist) usually means the assistant’s own setting.
→
(blocked-by-allowlist) usually means the assistant’s own setting.
Timeout / refused / DNS
→
a timeout, connection refused, or DNS failure usually means the corporate network or proxy.
→
a timeout, connection refused, or DNS failure usually means the corporate network or proxy.
Browser tools won’t work
Web assistants (claude.ai, chatgpt.com, and similar) can add the connector, but they can’t be configured to let their sandbox download from senzing.com – so recipes stall on install with no fix. Use a desktop app or IDE tool instead (Claude Code, Claude Desktop, Cursor, VS Code, Windsurf, and so on).
Claude Desktop app
Two settings matter, both under Claude Desktop’s Settings:
The connector
adds the Senzing tools (URL https://mcp.senzing.com/mcp, no authentication).
The code-execution domain allowlist
lets Claude’s sandbox reach mcp.senzing.com; needed only for recipes that install or download.
The exact place for each moves around as the app updates, so for where they live right now, ask Claude (“how do I add an MCP server?” / “how do I allow a domain for code execution?”) or check Anthropic’s docs below.
Good to know
(two non-obvious ones):
•
Domain-allowlist changes apply to new conversations only – start a fresh chat after saving.
•
Known bug: an allowed domain sometimes still returns 403 even when set correctly. If it fails after a fresh session, that’s a reported issue, not your mistake.
Authoritative, up-to-date docs (Anthropic)
Get started with custom connectors using remote MCP
support.claude.com · opens in a new tab
Create and edit files with Claude (covers code execution and network egress)
support.claude.com · opens in a new tab
