Use elicitation only where the version supports it

Elicitation forms and URL flows are not available in every MCP protocol version. Scope declarations and interaction examples to the versions that define the chosen mode. Describing an interaction does not make that interaction available in an older protocol version.

Requirement

Elicitation is used only from MCP 2025-06-18, and URL mode only from MCP 2025-11-25, in declarations and in Tool interaction steps.

Details

Rule ID: mcp.elicitation.protocol-version
Owner: mcp
Surface: ElicitRequest · Path: mode
Kind: structural
Requirement level: must
Status: internal · Enforcement: internal

Protocol version applicability

`2024-11-05`	`2025-03-26`	`2025-06-18`	`2025-11-25`	`2026-07-28`
applies	applies	applies	applies	applies

Required by

MCP Description 0.9.0, Sections 9.4 and 12.5
- 12. Elicitation Declarations: req-elicitation-protocol-versions
- 1. Tools: req-interaction-protocol-version-valid

Based on

Tier 1 — MCP schema.ts and normative specification text: MCP 2025-03-26 schema.ts (no elicitation/create); MCP 2025-06-18 schema.ts, ElicitRequest (form only); MCP 2025-11-25 and 2026-07-28 schema.ts, ElicitRequestURLParams (mode “url”)

Notes

Elicitation Declarations scoped before MCP 2025-06-18 are outside the complete semantic checks (Section 16.2).

Examples

Invalid example

Source: expected-invalid/elicitation-version-mismatch.json · Selected: /tools/0/elicitations/0

{
  "name": "authorize",
  "mode": "url",
  "message": "Authorize access.",
  "url": "https://auth.example.com/authorize"
}

Invalid example

Source: expected-invalid/invalid-tool-interaction-example-semantics.json · Selected: /tools/0/interactionExamples/broken/steps/0/request

{
  "mode": "url",
  "message": "Authorize publication.",
  "url": "https://mcp.example.com/release/connect"
}

Rule Source Code

elicitation.yaml at immutable tag v0.9.0-rc.3.