ssh_tunnel_open

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the burden of behavioral disclosure. It adds useful behavior: the tunnel lives until the end of the Claude Code session and is reachable at a returned address. It does not mention authentication, preconditions, or cleanup detail beyond the implied session lifetime.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is short and front-loaded with the purpose, followed by a concrete example and a key behavioral note. It is relatively efficient, though the example is slightly specific and could be tighter.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with six parameters, no annotations, no output schema, and a range of tunnel kinds plus many sibling tools, the description is not complete. It explains only a local-tunnel scenario and does not fully cover the tool's modes, argument expectations, or returned-address format.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 33%, so the description should compensate. It explains one meaningful example for kind='local', but does not clarify server, bind, listen_port, dest_host, or dest_port semantics across local/remote/dynamic modes. This leaves too much parameter behavior to be inferred.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific action ('open a tunnel to a server') and gives a concrete use case, which distinguishes this from sibling connection and shell tools. It could more explicitly call out SSH tunneling, but the object and behavior are clear.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives an example of when the tool is appropriate — exposing a locally-listening service through a tunnel — and notes the tunnel lifetime. It does not explicitly discuss when not to use it or contrast it with ssh_connect, ssh_shell_open, or ssh_run, so some guidance is present but not full.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.