Kalon for Mac is a Model Context Protocol client. A connected server's tools are offered to the agent next to the built-in tools. MCP, skills and plugins live together in Settings › Tools, which has three tabs: Plugins, MCP and Skills.
MCP is available on the Mac only. Skills work on both the Mac and iPhone.
Add an MCP server
- Open Settings › Tools and choose MCP.
- Click Add a server.
- Enter a Name and choose a transport: STDIO or Streamable HTTP.
- Fill in the fields for that transport, then click Save.
- Turn on In chat for the server. Servers are off in chat by default, because many tools at once can overwhelm a small model.
The row shows how many tools the server offers, or couldn't connect. Use Reconnect after changing something outside Kalon. The gear menu has Configure and Remove.
STDIO
Kalon starts the program and exchanges JSON-RPC messages with it over standard input and output.
| Field | Notes |
|---|---|
| Command to launch | The full path to the executable, for example /opt/homebrew/bin/npx. |
| Arguments | One per line, for example -y and @modelcontextprotocol/server-filesystem. |
| Environment variables | Key and value pairs. Values are stored in Kalon's settings. |
| Environment variable passthrough | Names of variables to take from Kalon's own environment, so a secret does not have to be stored. |
| Working directory | Optional, for example ~/code. |
Streamable HTTP
Kalon sends each request as an HTTP POST and accepts either a JSON or an event-stream reply.
| Field | Notes |
|---|---|
| URL | The server's endpoint, for example https://mcp.example.com/mcp. |
| Bearer token env var | The name of an environment variable that holds the token. The token itself is never stored in the configuration. |
| Headers | Extra request headers. |
| Headers from environment variables | Headers whose values are read from environment variables. |
OAuth
For HTTP servers that require sign-in, click Connect on the server's row. Kalon discovers the server's authorization endpoints, registers itself as a client, and opens your browser to approve access using PKCE. The browser returns to Kalon through kalon://oauth-callback. The row then shows Signed in; click it to sign out.
Tokens are stored in the macOS Keychain and refreshed automatically before they expire.
How tools reach the model
- Each tool is named
mcp__<server>__<tool>. - A tool that its server does not mark as read-only asks for approval before it runs.
- Results are trimmed to 12,000 characters before they go back to the model.
- With a local model, the number of MCP tools offered in one turn is capped to fit the context window, shared across servers. When a server's list is cut, its row says how many of its tools were offered.
- Calls time out after 60 seconds.
Kalon supports MCP tools. Resources, prompts and sampling are not used.
Skills
A skill is a Markdown file of instructions that turns Kalon into a specialist for one kind of task. Only each skill's name and description sit in the model's context. The full text is loaded with the skill tool when a task matches, so skills cost almost nothing until they are used. Skills never download or run anything themselves.
The Skills tab lists installed skills with a switch for each, and has New skill, a search field and a button to reveal the skills folder. Open a skill to Edit, Reveal or Uninstall it, or click Try in chat to attach it to your next message.
Kalon for Mac starts with git-review and make-pdf. The iPhone starts with explain-simply, proofread, summarise and remember-this. Skills on iPhone need Settings › Tools › Let Kalon use tools.
See Writing a skill for the file format.
Plugins
A plugin installs an MCP server together with its skills and starter prompts in one step. The catalogue is built into the app.
| Plugin | Description | Contents |
|---|---|---|
| GitHub | Triage PRs, issues, and code. | The GitHub MCP server and a PR review skill. Needs a GITHUB_PERSONAL_ACCESS_TOKEN. |
| Filesystem | Reach files beyond the workspace. | The filesystem MCP server, rooted at your home folder. |
| Memory | A durable knowledge graph. | The memory MCP server. |
Click Install to add a plugin's servers and skills, and Uninstall to remove them. Server changes take effect the next time Kalon launches. Plugin servers are started with npx, which fetches the server package the first time it runs. If a plugin server shows couldn't connect, open Configure and set Command to launch to the full path of npx.
Child profiles
MCP servers, plugins and tools are not available in a child profile.