mcat-cli 0.1.8

The model-context access tool for agents and humans

mcat-cli

The model-context access tool for agents and humans.

mcat is a CLI to interact with MCP servers from an endpoint.

mcat provides:

• auth start: start authorization and return action details (URL/code)
• auth continue: resume a paused auth flow
• init: run MCP initialize and store session info
• tool / resource / prompt: access server capabilities

Install

Example install commands:

pip install mcat-cli

uv tool install mcat-cli

Requires Python 3.11+.

Typical Flow

1. Start auth (non-blocking):

mcat auth start https://mcp.example.com/mcp \
  -k token.json \
  --state auth.json

2. Continue auth after browser approval:

mcat auth continue --state auth.json -k token.json

3. Initialize MCP session:

mcat init https://mcp.example.com/mcp -k token.json -o session.json

4. Discover and use server utilities:

mcat tool list -s session.json
mcat tool call TOOL_NAME -i '{"key":"value"}' -s session.json

mcat resource list -s session.json
mcat resource read RESOURCE_URI -s session.json

mcat prompt list -s session.json
mcat prompt get PROMPT_NAME -s session.json -i '{"arg":"value"}'

If you are a human using the CLI directly, add --wait to auth start:

mcat auth start https://mcp.example.com/mcp -k token.json --state auth.json --wait

Tokens and secrets

Tokens and secrets can be specified by -k/--key-ref and KEY_SPEC using these patterns:

• env://VAR
• .env://path:VAR
• .env://:VAR (same as .env://.env:VAR)
• json://path
• path (same as json://path)

Notes:

• auth writes token back to --key-ref
• existing destination needs -o/--overwrite
• env:// is read-only for writes

Examples:

• Existing token/PAT in environment variable:

mcat init https://mcp.example.com/mcp -k env://MCP_TOKEN -o session.json

• Existing token/PAT in .env file:

mcat init https://mcp.example.com/mcp -k .env://.env:MCP_TOKEN -o session.json

For GitHub MCP usage, if you already have a GitHub PAT, you can reference it from env://... or .env://... directly.

Provide OAuth Client Information

Use client config when a provider expects a specific OAuth client (for example, pre-registered client settings in services like Linear, or enterprise OAuth setups).

auth start supports:

• -c/--client CLIENT_INFO_FILE
• --client-id ID
• --client-secret KEY_SPEC
• --client-name NAME

Resolution order:

1. CLI overrides
2. --client file
3. built-in defaults

Modes:

• static client mode: resolved client_id present
• dynamic registration mode: no resolved client_id, uses resolved client_name

Validation:

• name conflicts with id/secret
• --client-name conflicts with --client-id/--client-secret
• secret requires id

Example client file (dynamic registration):

{"name":"your-public-client-name"}

Example client file (static client):

{
  "id": "your-client-id",
  "secret": "env://OAUTH_CLIENT_SECRET",
  "scope": "mcp:connect",
  "resource": "https://mcp.example.com/mcp"
}

Output

Most commands emit JSON to stdout:

{"ok":true,"result":{}}

{"ok":false,"error":"message"}

Resource output modes:

• mcat resource read ... -s session.json: JSON result
• mcat resource read ... -s session.json -o file.bin: save decoded content to file + JSON metadata
• mcat resource read ... -s session.json -o -: write decoded bytes to stdout

When logging is enabled, log output is sent to stderr by default.

Logging

If something goes wrong, enable logs for auth, mcp, and app:

mcat --log auth --log mcp --log app --log-stderr auth start ...

To include HTTP request/response bodies, use :debug level:

mcat --log auth:debug --log mcp:debug --log app:debug --log-stderr auth start ...

Logging options are global options and must be placed before the command name.