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Unblocked offers two ways to bring in a system that doesn’t have a built-in data source, and both appear under Settings › Data Sources › Custom. They work in opposite directions:
  • Custom data source via the API is a push model. You create a collection with the Unblocked REST API and upload documents to it. Unblocked indexes what you send and cites those documents in answers.
  • Custom MCP is a pull model. You connect a Model Context Protocol (MCP) server that is reachable over public HTTPS, and Unblocked calls its read-only tools while it answers a question. Nothing is ingested or indexed.
If Unblocked already has a built-in data source for the system — such as Datadog or Sentry — connect that instead. Built-in data sources are indexed, kept in sync, and cited in answers, so a Custom MCP passthrough to the same system gives you less.

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Compare the two options

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When to use the API custom data source

Use the API when the content behaves like a document set you can hand over:
  • The data is static or changes slowly, such as internal documentation, runbooks, policies, or exported reports.
  • You can build and upload the content on a cadence, for example nightly or after a publish step.
  • You don’t want to expose any infrastructure to the public internet.
  • Answers don’t need to reflect the state of a system at the moment the question is asked.
  • You want the content to appear as a cited reference in answers.
Start with the API quickstart to create a token, create a collection, and add documents. A team can have up to 25 collections, and each request can be up to 10 MB. See rate limits for the request limits that apply to API tokens.

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When to use Custom MCP

Use Custom MCP when the answer depends on the current state of a running system:
  • You need live context, such as querying a database, a dashboard, or an internal tool on demand.
  • No built-in Unblocked data source exists for the system. This covers internal tools, proprietary APIs, and platforms Unblocked doesn’t support yet, such as PagerDuty, Grafana, Backstage, LaunchDarkly, or Splunk.
  • The system can expose an MCP server over public HTTPS. Local, private-network, and plain-HTTP servers aren’t supported.
  • The server authenticates with OAuth or HTTP headers.
  • The tools you need are read-only. Unblocked uses annotations.readOnlyHint when the server provides it, and otherwise evaluates the tool description and excludes tools that might modify data.
See Custom MCP for the connection steps and troubleshooting.

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Rule of thumb

If you have a snapshot you can upload, use the API custom data source. If you have a live system you have to query, use Custom MCP. Some teams use both: uploaded collections for reference material that rarely changes, and a custom MCP server for the systems that have to be checked in the moment.