castDocs

Connect Hermes

Wire cast0 to Nous Research's Hermes Agent as an HTTP MCP server via prompt, CLI, or config file.

Hermes Agent connects to cast0 as a remote MCP server. The easiest way is to hand a prompt to Hermes and let it do the setup. Other options: run hermes mcp add, or edit ~/.hermes/config.yaml directly. All three end up with the same three tools available: create_episode, get_episode, list_episodes.

Paste this into Hermes. The agent wires up the MCP, prompts you for the key, and ships a test episode:

Set up cast0 so you can create podcast episodes for me. Add it as a remote MCP
server to Hermes. URL: https://api.cast0.ai/mcp?key=${CAST0_API_KEY}

- Tell me to go to https://cast0.ai, get the API key in format pk_..., and paste it to you.
- Save it as CAST0_API_KEY (`hermes config set CAST0_API_KEY pk_...`).
- Reload MCP.
- Create short test episode so I can confirm it's working.

For more info, see https://cast0.ai/docs/connect-hermes

The API key creates episodes on your podcast. Anyone with the key can publish to your feed. Keep ~/.hermes/.env out of version control.

CLI: hermes mcp add

Save your API key to ~/.hermes/.env

Sign in at cast0.ai, create a podcast, copy the API key (pk_...) from the podcast page, then append it to ~/.hermes/.env:

echo 'CAST0_API_KEY=pk_xxxxx' >> ~/.hermes/.env

Or:

hermes config set CAST0_API_KEY pk_xxxxx

Register the server

hermes mcp add cast0 --url "https://api.cast0.ai/mcp?key=\${CAST0_API_KEY}"

The backslash before ${CAST0_API_KEY} keeps the shell from expanding it. Hermes resolves the variable at connect time from ~/.hermes/.env.

When prompted "Does this server require authentication?", answer n. The API key is already in the URL.

Reload and test

In a running Hermes session:

/reload-mcp

Or test the connection from the CLI:

hermes mcp test cast0

Then ask Hermes to create a test episode.

Edit config directly

Add the server block

Open ~/.hermes/config.yaml and add under mcp_servers:

mcp_servers:
  cast0:
    url: "https://api.cast0.ai/mcp?key=${CAST0_API_KEY}"

Save your API key to ~/.hermes/.env

CAST0_API_KEY=pk_xxxxx

Get the key from cast0.ai after creating a podcast. Hermes loads this file and substitutes ${CAST0_API_KEY} into the URL when connecting.

Reload and test

/reload-mcp

Then ask Hermes to create a test episode. It lands in your RSS feed. Subscribe to that feed in any podcast app to listen.

What's next

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