Elicitation lets a server pause a tool call mid-execution to ask the user for more information, rather than failing outright or guessing at a missing value. MCPFlo renders these requests as an interactive form, right inside the call flow.

How it works

1. You invoke a tool as usual (see Schema-Driven Invocation Forms).
2. Mid-call, the server sends an elicitation/create request — declaring a JSON Schema for the information it needs, plus a message explaining why.
3. MCPFlo pauses the call and renders the requested schema as a form, along with the server’s message.
4. You fill in the form and submit — MCPFlo sends your answer back to the server as the elicitation response.
5. The server resumes the tool call using your answer, and the final result renders as normal.

Example use case

A deploy tool might elicit confirmation before proceeding (“Deploy to production? This will affect live traffic.”) or ask for a missing parameter it couldn’t infer (e.g. which environment to target), rather than requiring every possible parameter up front.

What’s supported

• Form-mode elicitation — the server declares a schema, MCPFlo renders a form, you submit structured data back. This is fully supported.

What’s not supported

• URL-mode elicitation — where a server directs the user to complete an action in a browser rather than filling out an inline form — is not currently supported.

Why this matters for testing

Elicitation is one of the trickier parts of the MCP protocol to get right as a server author — it requires correctly pausing execution, waiting for a response, and resuming with the right state. MCPFlo lets you exercise this flow directly and confirm:

• The elicited schema renders and validates correctly.
• Your response is correctly incorporated into the tool’s continued execution.
• The tool’s final result reflects the elicited value as expected.

Related

• See Sampling for the reverse case — a server asking the client to run a model completion, rather than asking the user a direct question.
• The bundled test-fixture server, @mcpflo/server-everything, includes a tool that exercises elicitation — a good way to see this flow working before testing your own server.