MCC — Model Context Catalog

An MCP server that exposes Python functions and shell commands as a permission-controlled tool catalog. Claude and other LLM clients discover and call tools through a unified search / execute interface, with RBAC and pluggable authentication built in.

Features

• Serve multiple tools from one MCP by exposing Python functions or shell/exec commands
• Published catalog of tools for easy discoverability and llm execution
• Built in RBAC with user management and tool groups
• Multiple auth backends (dev unauthed, Github OAuth2, PAT)
• Optional contrib toolsets (utils and OSINT) loaded via MCC_SETTINGS_FILES
• CLI management of users and tools
• Async tool support

How it works

Tools are defined in YAML files pointing at Python callables. MCC loads them, enforces per-user permissions, and serves them to any LLM via MCP.

Claude → search("deploy") → ["myteam.deploy - Deploys the app  execute(environment: str = 'dev')"]
Claude → execute("myteam.deploy", {"environment": "prod"})  →  result

Quickstart

uv add model-context-catalog

1. Configure auth (settings.local.yaml):

auth: dev-admin   # dev mode: no auth

2. Add an admin user:

mcc user add -u alice -e alice@example.com -g admin

3. Run the server:

python -m mcc.app

4. Point your MCP client at the HTTP endpoint.

Defining Tools

Create a YAML file anywhere:

group: myteam
tools:
  - fn: mypackage.mymodule:my_function     # required: dotted import path
    name: my-tool                          # optional: defaults to __name__
    description: "Does something useful"   # optional: defaults to __doc__
    params:                                # optional: introspected from signature
      - name: message
        type: str          # str | int | float | bool | list | dict
        required: true
      - name: flag
        type: bool
        override: true     # always injected at call time, hidden from callers

Exec Tools (External Commands)

Run any command — Node, Go, shell scripts — as a catalog tool:

tools:
  # Interpolation mode (default): params formatted into command string
  - name: grep
    exec: "grep -rn {pattern} {path}"
    params:
      - name: pattern
        type: str
        required: true
      - name: path
        type: str
        default: "."

  # Stdin mode: params sent as JSON on stdin
  - name: lint
    exec: "node tools/lint.js"
    stdin: true
    timeout: 30
    params:
      - name: file
        type: str
        required: true

  # With resource limits (unix only)
  - name: sandbox
    exec: "python3 untrusted.py"
    stdin: true
    timeout: 10
    limits:
      mem_mb: 256
      cpu_sec: 5
      fsize_mb: 50
      nofile: 128

Exec tools always return (returncode, stdout, stderr). Params must be declared in YAML (no signature to introspect).

⚠ Security: With stdin: false (the default), parameters are interpolated directly into the shell command. Do not expose exec tools with user-controlled params to untrusted callers without additional input validation.

Register it in settings.local.yaml:

tools:
  - path/to/mytools.yaml

To load optional contrib toolsets, use MCC_SETTINGS_FILES:

# utils — HTTP, filesystem, shell, text, time, archives
MCC_SETTINGS_FILES=toolsets/contrib/settings.yaml

# OSINT — threat intel, corporate records, geolocation, and more
MCC_SETTINGS_FILES=toolsets/osint/settings.yaml

# both
MCC_SETTINGS_FILES=toolsets/contrib/settings.yaml;toolsets/osint/settings.yaml

Authentication

Switch backends via auth in settings:

GitHub PAT config:

default:
  auth: "github_pat"

  github_pat:
    token: "ghp_..."

GitHub OAuth config:

default:
  auth: "github_oauth"

  github_oauth:
    client_id: "..."
    client_secret: "..."
    base_url: "https://your-server.example.com"

User & Permission Management

mcc user add -u alice -e alice@example.com -g myteam
mcc user add -u bob -g admin
mcc user list
mcc user grant alice -g ops -t custom.tool
mcc user revoke alice -t custom.tool
mcc user remove alice

Permission hierarchy (first match wins):

1. Tool is in the public group → anyone can access
2. User is in the admin group → can access everything
3. User's groups include the tool's group → allowed
4. Tool key is in the user's explicit tool grants → allowed

Documentation

• Getting Started — installation, quickstart, configuration
• Tools — YAML format, Python tools, exec tools, parameters, resource limits
• Auth & Permissions — backends, users, groups
• Contrib Toolsets — utils (HTTP, filesystem, shell, text, time, archives) and OSINT (threat intel, corporate records, geolocation, and more)

See openspec/project.md for a full architectural breakdown. Inspiration How to build an enterprise-grade MCP registry