> ## Documentation Index
> Fetch the complete documentation index at: https://mcp-docs.cohesive.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> How the Cohesive MCP server authenticates a caller, what it runs tools under, and what that identity can't do.

There's one way in: you sign in to Cohesive. The client handles the OAuth flow, and every tool call afterwards runs under you. The server holds no credential of its own — there's no identity to fall back on if yours is rejected.

## The sign-in

The server is its own authorization server, and brokers the real sign-in to Cohesive, so the client never talks to the identity provider directly.

<Steps>
  <Step title="The client discovers where to sign in">
    An unauthenticated request returns `401` with a challenge pointing at the resource metadata, which names the authorization server.
  </Step>

  <Step title="You sign in">
    The client sends you to Cohesive with an authorization code request and PKCE. You approve, and the browser hands you back.
  </Step>

  <Step title="The client receives a session">
    The code is exchanged for an org-scoped access token. Refresh tokens are supported, so a connection outlives a single access token.
  </Step>
</Steps>

Nothing in that sequence asks you for a value to copy. If a client asks you to paste something other than the server URL, it isn't this flow.

## What tools actually run under

Your session isn't what does the work. On each request the server mints a short-lived *MCP token* from it — your identity, your access to the organization, and a claim marking the session as MCP — and tools run under that.

A session that has expired or can't be verified is refused, and nothing falls back to another identity: acting as you is the whole point.

## What an MCP session can't do

The `mcp` claim withholds credential management. Connected through this server, an agent acting as you can work across your Workspaces, and it cannot:

* Create, list, or revoke credentials for your account
* Read or change harness credentials

Everything else is your own access, unchanged. If you can't reach a Canvas in the app, the agent can't either.

## Revocation

End a session and the effect is immediate, not an hour later. When a tool call comes back with an authentication failure, the server drops what it cached for that session, so the next request re-mints — or is refused.

## Challenges and metadata

An unauthenticated request gets a `401` with a `WWW-Authenticate: Bearer realm="cohesive"` challenge and a pointer to the resource metadata, which is where a client discovers the authorization server:

```bash theme={null}
curl https://mcp.cohesive.ai/.well-known/oauth-protected-resource/mcp
```

```json theme={null}
{
  "resource": "https://mcp.cohesive.ai/mcp",
  "authorization_servers": ["https://mcp.cohesive.ai"],
  "bearer_methods_supported": ["header"],
  "resource_name": "Cohesive MCP"
}
```

An authentication failure inside a tool call comes back differently — as a tool result with exit code 3. See [Results](/reference/results).