The check before the call.

Checked before reliance, the same pair produces a report with 13 checks: 12 pass, and the one that fails names the missing field.

1. 01Supply a capability snapshot
2. 02State the caller’s workflow requirements
3. 03Receive bounded compatibility evidence

From a terminal or MCP client

curl -sS https://exactlane.dev/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: check_mcp_capability' \
  --data-binary @- <<JSON
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "_meta": {
      "io.modelcontextprotocol/protocolVersion": "2026-07-28",
      "io.modelcontextprotocol/clientCapabilities": {}
    },
    "name": "check_mcp_capability",
    "arguments": {
      "capability_key": "quickstart-scheduler",
      "revision_label": "rev-42",
      "snapshot": {
        "schema_version": "exactlane.mcp-snapshot/0.1",
        "protocol": {"name": "mcp", "revision": "2026-07-28", "transport": "streamable-http"},
        "captured_at": "$(date -u +%Y-%m-%dT%H:%M:%SZ)",
        "tools": [{
          "name": "schedule_jobs",
          "max_input_bytes": 262144,
          "inputSchema": {
            "type": "object",
            "properties": {"jobs": {"type": "array", "items": {"type": "object", "properties": {}}}},
            "required": ["jobs"],
            "additionalProperties": false
          },
          "outputSchema": {
            "type": "object",
            "properties": {"assignments": {"type": "array", "items": {
              "type": "object",
              "properties": {"job_id": {"type": "string"}},
              "required": ["job_id"],
              "additionalProperties": false
            }}},
            "required": ["assignments"],
            "additionalProperties": false
          }
        }]
      },
      "requirements": {
        "schema_version": "exactlane.consumer-requirements/0.3",
        "protocol_revision": "2026-07-28",
        "transport": "streamable-http",
        "max_snapshot_age_seconds": 86400,
        "required_tools": [{
          "name": "schedule_jobs",
          "provided_input_fields": {"jobs": "array"},
          "required_output_paths": {
            "assignments[].job_id": "string",
            "assignments[].start_ms": "integer"
          },
          "estimated_input_bytes": 4096
        }]
      }
    }
  }
}
JSON

• The report is at result.structuredContent.report: verdict is FAIL, 12 of 13 checks pass, and tool:schedule_jobs:output:assignments[].start_ms is the one that fails.
• Runs in bash or zsh. The heredoc fills captured_at with the current UTC time, so the 24-hour freshness requirement passes.
• Calling REST instead? profile.version must match requirements.schema_version: 0.3 pairs with exactlane.consumer-requirements/0.3, and the frozen 0.2 and 0.1 profiles pair the same way. A mismatch returns 422 PROFILE_REQUIREMENTS_VERSION_MISMATCH and no report. The MCP tool infers the profile from the requirements.
• Each call issues and revokes its own short-lived Preview grant, so Preview issuance rate limits apply.

05 / Evidence boundary

• PASS

  Every check ran with supported semantics and met the requirement.

  A snapshot that still declares start_ms: all 13 checks pass.

• FAIL

  A concrete incompatibility was proven.

  tool:schedule_jobs:presence observed MISSING. Its 7 dependent checks are NOT_RUN, and FAIL still decides the verdict.

• INCOMPLETE

  Evidence was missing or stale, so a check did not run.

  snapshot:freshness is NOT_RUN: the snapshot is 820800 seconds old and the requirement allows 86400.

• UNSUPPORTED

  Exactlane did not decide.

  protocol:revision observed 2025-11-25; this profile evaluates 2026-07-28 only.

Each example is actual evaluator output. A report has one verdict: any ERROR gives SYSTEM_ERROR; otherwise any FAIL gives FAIL; otherwise any UNSUPPORTED gives UNSUPPORTED; otherwise any NOT_RUN gives INCOMPLETE; otherwise PASS.

Exactlane does not make the caller’s operational decision, and no verdict maps to an action. The caller owns CONTINUE / UPDATE_INTEGRATION / HOLD.