Source: https://harnsy.dev/docs/external-tools

> MCP servers give your agents outside tools: a repository host, a tracker, a database. You connect a server once, check what its tools do, and say which projects and roles may use them.

# MCP servers

MCP servers give your agents outside tools: a repository host, a tracker, a database. You connect a server once, check what its tools do, and say which projects and roles may use them.

**Connect.** Settings › Services for agents › “MCP”. Press “Connect a server”, or pick one from the built-in catalog of ready services. Paste its key, or sign in through the service’s OAuth in your browser (harnsy keeps the token and refreshes it); you can also type a server’s https address. The connection’s name is lowercase Latin letters and digits, up to 16; it names the tools `ext_<name>_<tool>`. When the server has a read-only address, it is offered.

**Review the tools.** “Tools: N” lists them with the server’s own labels: reads, writes, destructive. A server can mislabel a tool. New or changed tools are marked. Read-only tools are allowed at first; tick the others agents may use, then “Save tools”; “Refresh tools” reads the list again.

**Say who may use them.** “Access” per project and role. The switch “Leads grant connections” lets a lead give the servers that are on to roles of its own project; a lead cannot connect a server, see a key or allow a tool.

**What waits for your yes.** “Calls waiting for your yes” with “Yes, run it” and “No”. An undecided call expires after 24 hours, and the agent is told. A call waits when: “Confirm every write” is on; the server is under strict control and the tool may delete data; the tool is marked as deleting; the arguments carry a secret of this machine; or after 30 writes through one connection within 5 minutes. A server’s answer reaches the agent marked as the server’s data, with the key blanked.

**The call log.** Every call is logged: who, which tool, and the status (done, failed, refused, waits for you, declined, running). A write that ran without your yes also keeps a short summary of its arguments.

**Remove.** The key is erased here, its grants go and agents lose its tools. The key still works at the service: revoke it there too.

**What it contacts.** harnsy calls the server at the https address you gave, with its key, when you connect, list tools or an agent calls one; OAuth hosts are those named in the server’s metadata.

Since harnsy 0.10.0.

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