open

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

With no annotations provided, the description carries the full burden and excels. It discloses idempotency, server-owned connection that 'survives any gap between tool calls,' no automatic reconnection, session-death notification, and the requirement to send '~z' on a fresh line. This is rich, non-obvious behavioral context that significantly aids the agent.

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 concise yet information-dense. It leads with a clear purpose, then adds essential behavioral caveats, and finishes with an actionable protocol note. Every sentence earns its place with no redundancy or fluff.

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 stateful connection tool with no output schema and no annotations, the description is remarkably complete. It covers the connection lifecycle (open, idempotent reopen, server ownership, survival, no auto-reconnect, explicit reconnection), failure reporting ('you will be told'), and the initialization sequence (^Z). This is sufficient for an agent to use 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 description does not add any parameter-specific meaning, but the input schema covers 100% of the parameters with clear descriptions ('Emulator host; defaults to the configured host' and similar). Per the rubric, baseline 3 applies when schema coverage is high, and the description need not compensate.

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 clearly states the specific action: 'Open the single TCP terminal line to the PDP-10.' This uses a specific verb ('open') and resource ('single TCP terminal line to the PDP-10'), which distinguishes it from sibling tools like send, read, peek, status, and close.

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 implies when to use the tool: to establish or re-establish the connection. It explains idempotent behavior ('if the line is already open this reports status instead of reconnecting') and the lack of auto-reconnect, guiding the agent to explicitly reopen if the session dies. However, it does not explicitly mention the sibling 'status' tool as an alternative when only checking connection state, so it falls short of full exclusion guidance.

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