pty_open

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

With no annotations, the description carries the full burden, and it does well: it discloses that sessions persist across server/client restarts, that the backend is resident, and that platform-specific backends (tmux/psmux) are used. It does not mention cleanup, failure modes, or resource implications, but the main behavioral surprise—persistence—is clearly highlighted.

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 three dense, purposeful sentences: purpose and return value first, persistence semantics second, and a concrete usage example third. There is no filler or redundant restatement.

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?

Given the low complexity, no annotations, and no output schema, the description covers the essential invocation contract: what is created, what is returned (session_id), why sessions persist, and how to interact with the terminal afterward. It could add exact response shape and failure conditions, but these are not critical for selecting and invoking the tool correctly.

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?

The input schema already documents both parameters (name and shell) with 100% schema_description_coverage, so the baseline is 3. The description adds no additional semantic detail about the parameters themselves, which is acceptable given the schema coverage.

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 the exact operation: opens one local persistent terminal (tmux on POSIX, psmux on Windows) and returns a session_id. It clearly stands apart from siblings like pty_read, pty_send, pty_list, and pty_close by describing the creation action.

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 explicitly tells the agent how to perform remote operations: do not use a dedicated tool; instead launch a terminal with pty_open and then run pty_send(session_id, "ssh host") inside it. This gives clear when-to-use and how-to-use guidance relative to the pty_* sibling tools.

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