agent-tokens

title

Agent Tokens

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Agent Tokens

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description

Scoped API credentials for AI agents with server and permission restrictions

keywords

agent

tokens

authentication

security

scoping

permissions

mcp

Agent Tokens

Agent tokens provide scoped, revocable credentials for AI agents connecting to MCPProxy. Instead of sharing the admin API key with every agent, each agent gets its own token with restricted access to specific servers and permission tiers.

Why Agent Tokens?

MCPProxy sits between AI agents and upstream MCP servers. Without agent tokens, every connection gets full admin access — any agent can call any tool on any server with no restrictions.

This creates real problems:

A CI/CD bot that only needs to read GitHub issues can also delete repositories
A monitoring agent that checks server status can also modify configurations
A compromised agent has unlimited access to all upstream servers
No audit trail — you can't tell which agent performed which action

Agent tokens solve this with defense-in-depth scoping:

┌─────────────────────────────────────────┐
│  AI Agent (e.g., deploy-bot)            │
│  Token: mcp_agt_a1b2c3...              │
│  Servers: github, gitlab                │
│  Permissions: read, write               │
└──────────────┬──────────────────────────┘
               │
               ▼
┌─────────────────────────────────────────┐
│  MCPProxy                               │
│                                         │
│  1. retrieve_tools → filters results    │
│     to github + gitlab only             │
│                                         │
│  2. call_tool_write → allowed           │
│  3. call_tool_destructive → BLOCKED     │
│  4. call_tool_read(slack:...) → BLOCKED │
└─────────────────────────────────────────┘

Token Format

Agent tokens use the mcp_agt_ prefix followed by 64 hex characters:

mcp_agt_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2

Tokens are hashed with HMAC-SHA256 before storage — the raw token is shown once at creation and cannot be retrieved again.

Quick Start

Create a Token

mcpproxy token create \
  --name deploy-bot \
  --servers github,gitlab \
  --permissions read,write \
  --expires 30d

Output:

Agent token created successfully.

  Token: mcp_agt_a1b2c3d4...

  IMPORTANT: Save this token now. It cannot be retrieved again.

  Name:        deploy-bot
  Servers:     github, gitlab
  Permissions: read, write
  Expires:     2026-04-05 14:30

Use the Token

Agents authenticate by passing the token via any standard method:

# X-API-Key header
curl -H "X-API-Key: mcp_agt_a1b2c3d4..." http://localhost:8080/mcp

# Authorization: Bearer header
curl -H "Authorization: Bearer mcp_agt_a1b2c3d4..." http://localhost:8080/mcp

# Query parameter
curl "http://localhost:8080/mcp?apikey=mcp_agt_a1b2c3d4..."

In MCP client configurations:

{
  "mcpServers": {
    "mcpproxy": {
      "url": "http://localhost:8080/mcp",
      "headers": {
        "X-API-Key": "mcp_agt_a1b2c3d4..."
      }
    }
  }
}

Enforcing Authentication on /mcp

By default, the /mcp endpoint allows unauthenticated access for backward compatibility with existing MCP clients. This means agent tokens are optional — agents that don't provide a token get full admin access.

To make agent tokens mandatory, enable require_mcp_auth:

{
  "require_mcp_auth": true
}

Or via CLI flag:

mcpproxy serve --require-mcp-auth

With this enabled:

Requests without a token → 401 Unauthorized
Requests with an invalid token → 401 Unauthorized
Requests with a valid agent token → scoped access
Requests with the admin API key → full admin access
Tray/socket connections → always trusted (OS-level auth)

Recommended setup: Enable require_mcp_auth when deploying MCPProxy in environments where multiple agents connect, or when you want to enforce least-privilege access.

Permission Tiers

Each token specifies which permission tiers the agent can use:

Permission	Tool Variants Allowed	Use Case
`read`	`call_tool_read`	Monitoring, querying, status checks
`write`	`call_tool_read`, `call_tool_write`	Creating issues, updating records
`destructive`	All variants	Deleting resources, admin operations

Permissions are cumulative — write implies read, and destructive implies both. The read permission is always required.

# Read-only monitoring agent
mcpproxy token create --name monitor --servers "*" --permissions read

# CI/CD agent that creates and updates
mcpproxy token create --name ci-agent --servers github --permissions read,write

# Full-access admin agent
mcpproxy token create --name admin-bot --servers "*" --permissions read,write,destructive

Server Scoping

Tokens restrict which upstream servers an agent can access:

# Only GitHub and GitLab
mcpproxy token create --name deploy-bot --servers github,gitlab --permissions read,write

# All servers (wildcard)
mcpproxy token create --name all-access --servers "*" --permissions read

Server scoping is enforced at two levels:

Tool discovery (retrieve_tools) — only returns tools from allowed servers
Tool execution (call_tool_*) — blocks calls to out-of-scope servers

Managing Tokens

List All Tokens

mcpproxy token list

NAME                 PREFIX         SERVERS                   PERMISSIONS          REVOKED  EXPIRES
deploy-bot           mcp_agt_a1b2   github,gitlab             read,write           no       2026-04-05 14:30
monitor              mcp_agt_c3d4   *                         read                 no       2026-04-05 14:30
old-bot              mcp_agt_e5f6   github                    read                 yes      2026-03-01 10:00

Show Token Details

mcpproxy token show deploy-bot

Revoke a Token

Immediately invalidates the token:

mcpproxy token revoke deploy-bot

Regenerate a Token

Invalidates the old secret and generates a new one, keeping the same name and settings:

mcpproxy token regenerate deploy-bot

The new token is displayed once — save it immediately.

JSON Output

All commands support JSON output for scripting:

mcpproxy token list -o json
mcpproxy token create --name bot --servers github --permissions read -o json

Activity Logging

Agent token usage is tracked in the activity log. Each tool call records the agent identity:

# Filter activity by agent
mcpproxy activity list --agent deploy-bot

# Filter by auth type
mcpproxy activity list --auth-type agent
mcpproxy activity list --auth-type admin

Activity records include _auth_type, _auth_agent, and _auth_token_prefix metadata fields for audit trails.

REST API

Agent tokens can also be managed via the REST API (requires admin API key):

Method	Endpoint	Description
`POST`	`/api/v1/tokens`	Create a new agent token
`GET`	`/api/v1/tokens`	List all tokens
`GET`	`/api/v1/tokens/{name}`	Get token details
`DELETE`	`/api/v1/tokens/{name}`	Revoke a token
`POST`	`/api/v1/tokens/{name}/regenerate`	Regenerate token secret

Create Token via API

curl -X POST http://localhost:8080/api/v1/tokens \
  -H "X-API-Key: your-admin-key" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "deploy-bot",
    "allowed_servers": ["github", "gitlab"],
    "permissions": ["read", "write"],
    "expires_in": "30d"
  }'

Security Model

HMAC-SHA256 hashing — raw tokens are never stored; only HMAC hashes are persisted
Constant-time comparison — prevents timing attacks during token validation
Automatic expiry — tokens expire after a configurable duration (default: 30 days)
Revocation — tokens can be immediately invalidated
Prefix identification — the mcp_agt_ prefix distinguishes agent tokens from admin API keys without database lookups
Tray bypass — local tray/socket connections always get admin access (authenticated by OS-level socket permissions)

Configuration Reference

Config File

{
  "require_mcp_auth": false,
  "api_key": "your-admin-key"
}

Field	Type	Default	Description
`require_mcp_auth`	bool	`false`	Require authentication on `/mcp` endpoint
`api_key`	string	auto-generated	Admin API key for full access

CLI Flags

mcpproxy serve --require-mcp-auth    # Enforce /mcp authentication

Token Create Flags

Flag	Required	Default	Description
`--name`	Yes	—	Unique token name
`--servers`	Yes	—	Comma-separated server names or `"*"`
`--permissions`	Yes	—	Comma-separated: `read`, `write`, `destructive`
`--expires`	No	`30d`	Expiry duration (e.g., `7d`, `90d`, `365d`)

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Agent Tokens

Why Agent Tokens?

Token Format

Quick Start

Create a Token

Use the Token

Enforcing Authentication on /mcp

Permission Tiers

Server Scoping

Managing Tokens

List All Tokens

Show Token Details

Revoke a Token

Regenerate a Token

JSON Output

Activity Logging

REST API

Create Token via API

Security Model

Configuration Reference

Config File

CLI Flags

Token Create Flags

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Agent Tokens

Why Agent Tokens?

Token Format

Quick Start

Create a Token

Use the Token

Enforcing Authentication on /mcp

Permission Tiers

Server Scoping

Managing Tokens

List All Tokens

Show Token Details

Revoke a Token

Regenerate a Token

JSON Output

Activity Logging

REST API

Create Token via API

Security Model

Configuration Reference

Config File

CLI Flags

Token Create Flags