McpSource.ElicitationToRequest

C# · package Toolnexus · SPEC §2 · McpSource.cs

public static Request ElicitationToRequest(ElicitRequestParams p)
public static ElicitResult AnswerToElicitResult(Answer answer)

The bridge between MCP’s elicitation/create (a server asking you for input mid-tools/call) and toolnexus’s own §10 suspension contract (Request / Answer, in Suspension.cs) that a host resolves through waitFor. Two pure, byte-parity-tested mappings, always used as a pair:

ElicitationToRequest — an MCP ElicitRequestParams becomes a Request. Form mode (a JSON-Schema prompt) maps to Kind == "input" with the schema carried in Data["schema"]. URL mode maps to Kind == "authorization" with the Url set and no Data.
AnswerToElicitResult — the resolved Answer maps back to MCP’s ElicitResult: Ok == true → "accept" (with Data as the result content); Ok == false, Reason == "declined" → "decline"; anything else (cancelled, expired, no reason) → "cancel".

Both are used internally by McpSource.LoadAsync’s waitFor wiring — you call them directly only when building your own elicitation handler or testing the mapping itself.

When to use it

You are wiring a custom MCP client options / elicitation handler and want the exact same Request/Answer shape the built-in waitFor bridge produces — so a UI or approval flow written against §10 handles MCP elicitation identically to every other suspension source (the question builtin, HTTP auth, anything else that suspends).

Why this and not the alternative

Examples

1. Form mode maps to `kind:"input"` with the schema

using ModelContextProtocol.Protocol;
using Toolnexus;

var schema = new ElicitRequestParams.RequestSchema
{
    Properties = new Dictionary<string, ElicitRequestParams.PrimitiveSchemaDefinition>
    {
        ["name"] = new ElicitRequestParams.StringSchema(),
    },
    Required = new List<string> { "name" },
};

var req = McpSource.ElicitationToRequest(new ElicitRequestParams { Message = "Your name?", RequestedSchema = schema });

if (req.Kind != "input") throw new Exception(req.Kind);
if (req.Prompt != "Your name?") throw new Exception(req.Prompt);
if (req.Url != null) throw new Exception("form mode carries no url");
if (!ReferenceEquals(req.Data!["schema"], schema)) throw new Exception("schema not carried through");

Console.WriteLine($"ok: {req.Kind} — {req.Prompt}");

2. URL mode maps to `kind:"authorization"` with the URL

using ModelContextProtocol.Protocol;
using Toolnexus;

var req = McpSource.ElicitationToRequest(new ElicitRequestParams
{
    Mode = "url",
    Message = "Log in to continue",
    Url = "https://example.com/auth",
});

if (req.Kind != "authorization") throw new Exception(req.Kind);
if (req.Url != "https://example.com/auth") throw new Exception(req.Url);
if (req.Data != null) throw new Exception("url mode carries no schema");

Console.WriteLine($"ok: {req.Kind} -> {req.Url}");

3. Answer round-trips to accept / decline / cancel

using Toolnexus;

var accept = McpSource.AnswerToElicitResult(new Answer
{
    Id = "1", Ok = true, Data = new Dictionary<string, object?> { ["name"] = "Ada" },
});
if (accept.Action != "accept") throw new Exception(accept.Action);
if (accept.Content!["name"].GetString() != "Ada") throw new Exception("content not carried through");

var declined = McpSource.AnswerToElicitResult(new Answer { Id = "1", Ok = false, Reason = "declined" });
if (declined.Action != "decline") throw new Exception(declined.Action);

// Anything that isn't an explicit "declined" reason — including no reason at all — is a cancel.
var expired = McpSource.AnswerToElicitResult(new Answer { Id = "1", Ok = false, Reason = "expired" });
var noReason = McpSource.AnswerToElicitResult(new Answer { Id = "1", Ok = false });
if (expired.Action != "cancel" || noReason.Action != "cancel")
    throw new Exception($"{expired.Action},{noReason.Action}");

Console.WriteLine($"ok: {accept.Action} / {declined.Action} / {expired.Action}");

Mapping

MCP `ElicitRequestParams`	`Request`
`Mode` absent / `"form"`	`Kind = "input"`	`Data["schema"] = RequestedSchema`
`Mode = "url"`	`Kind = "authorization"`	`Url = Url`, no `Data`
`Message`	`Prompt`

`Answer`	MCP `ElicitResult.Action`
`Ok = true`	`"accept"` (`Content` from `Answer.Data`)
`Ok = false, Reason = "declined"`	`"decline"`
`Ok = false`, any other/no reason	`"cancel"`