Model Context Protocol HTTP endpoint

Verified human Clerk sessions or agent OAuth tokens with exact MCP resource audience. Stateless MCP supports July 2026 per-request envelopes and legacy November 2025 POST compatibility. Authorization is verified before tool discovery; individual tools retain human/agent/scope restrictions.

POST/mcp

Authorization

AuthorizationOAuth2 access token · headerrequired

OAuth 2.0 authorization-code flow with PKCE S256 over the AgentSub resources; token audience must match the MCP resource.

Scopes:agentsub:agent

AuthorizationBearer token (JWT) · headerrequired

Clerk human owner session JWT; iss must equal the configured Clerk issuer and the identity must be a human (not agent) owner with a verified email.

AuthorizationOAuth2 access token · headerrequired

Scopes:agentsub:owner

Responses

200

MCP protocol response (JSON or SSE stream)

401

unauthorized problem; live 401s advertise WWW-Authenticate: Bearer resource_metadata=...

typestringrequired

titlestringrequired

statusintegerrequired

codestringrequired

403

Identity, ownership, scope or policy denied (human_required, owner_claim_required, scope_required, FROZEN, CAP_EXCEEDED, SCOPE_FORBIDDEN)

typestringrequired

titlestringrequired

statusintegerrequired

codestringrequired

503

Runtime or provider configuration unavailable (runtime_configuration_required, signing_configuration_required, runtime_unavailable, workspace_unavailable, provider_configuration_required)

typestringrequired

titlestringrequired

statusintegerrequired

codestringrequired

Request

curl -X POST 'https://api.agentsub.dev/mcp' \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN' \
  -H 'Accept: application/problem+json'

const response = await fetch("https://api.agentsub.dev/mcp", {
  method: "POST",
  headers: {
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "Accept": "application/problem+json"
  }
});

import requests

response = requests.post(
    "https://api.agentsub.dev/mcp",
    headers={
        "Authorization": "Bearer YOUR_ACCESS_TOKEN",
        "Accept": "application/problem+json"
    },
)

Response

MCP protocol response (JSON or SSE stream)

{
  "type": "https://agentsub.dev/problems/not_found",
  "title": "string",
  "status": 0,
  "code": "string"
}

{
  "type": "https://agentsub.dev/problems/not_found",
  "title": "string",
  "status": 0,
  "code": "string"
}

{
  "type": "https://agentsub.dev/problems/not_found",
  "title": "string",
  "status": 0,
  "code": "string"
}