REST API
The API can run a saved Expert with parameters and target devices. The documentation describes authorisation and response formats.
Section 03 / Software
APIs and integrations
Connect your system to Extella.
REST API, MCP and a bridge to development tools let external applications call Extella and add it to a workflow.
Why it helps
Keep an existing interface and call the Extella capabilities you need from your own program.
What it contains
MCP
MCP is a standard way to connect Extella tools to compatible AI clients. The documentation provides an endpoint using Streamable HTTP.
Codex / Claude Code
The bridge connects Extella to local development tools. Its setup and permissions determine which actions a particular connection can perform.
Connections to systems
Integrations connect programs to external systems and data sources. Each connection needs an appropriate tool and permission to access its source.
What was measured
Extella measurements, September and October 2026. Each number holds under the conditions given.
- Tool descriptions take 10 times less space.
A custom MCP server on top of the Extella API gives the model 6 tools and 3.2 kilobytes of descriptions. The standard one gives 44 tools and 33 kilobytes on the same set of fields (02.10.2026). The shorter the descriptions, the fewer tokens the model spends in every conversation.
- Another MCP server connects as a language.
A call to a tool of another MCP server is saved as an expert of its own language and runs like any other expert, without a separate service.
- A language connects with one registration.
Registering a language handler on a device is one call, from 6.8 to 7.9 seconds (01.10.2026). A language released a few months before the test worked as an expert language on a server (16.10.2026).
- Channel limits.
A request body from a window is up to 64 kilobytes, a response is best kept under 200 kilobytes, and calls go up to 30 per minute. At about the 51st second the platform defers the response, so the state of long work is read with a separate lightweight expert.
- Empty values do not arrive.
The platform drops parameters whose value is 0, an empty string, false or null. Pass numbers and flags that can be zero or false as strings.
Articles and demos
DocumentationAPI and MCPAccess, requests, responses and checking a run: calling saved programs from your code or from an agent.DemoA report on the machine that holds the fileOne saved program reads a CSV file on the server that holds it; choose the parameters and the server.What it shows: Compute where the data is: the program goes to the file, not the file to the cloud. One saved program runs on any prepared machine chosen in the call, with no model in the run.DemoOne rule, three cabinetsA company rule written in words becomes a policy, and three running applications follow it at once.What it shows: A company rule is written once in words and applies at once in three running applications; every decision shows which check fired.
Related articles and examples.