pty_key

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals a significant behavioral trait: in Claude sessions, only C-c is permitted to preserve turn correlation, and that approval actions should be routed to claude_approval. However, it does not discuss error handling or consequences of sending disallowed keys, though the restriction itself is valuable transparency.

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 two sentences, front-loaded with the core action and immediately followed by a key usage rule. Every word serves a purpose: examples clarify the key parameter, and the restriction clarifies boundary conditions. No redundancy or filler.

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 simple tool with no output schema and no annotations, the description covers purpose, parameter examples, and usage restrictions, and relates it to sibling tools. It does not explain session_id or return behavior, but these are less critical given the tool's straightforward nature and the presence of sibling tools like pty_list and pty_open that likely establish session context.

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 schema covers only 50% of parameters (key has a description, session_id does not). The description adds meaning to the key parameter by listing acceptable aliases (C-c, C-d, Enter, Tab, Up, Down) and specifying a contextual restriction (only C-c in Claude sessions), compensating for the schema gap. session_id remains undocumented in both, but its purpose is implied as a session identifier.

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 tool's function with a specific verb ('送る' / send) and resource ('制御キー' / control keys), and provides concrete examples (C-c, C-d, Enter, Tab, Up, Down) that distinguish it from sibling tools like pty_send (which likely sends arbitrary text) and claude_approval (which handles approval UI).

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 states when to use this tool and provides an exclusion: 'In aiterm-correlated Claude sessions, only C-c is allowed to maintain turn correlation, and the approval UI is operated with claude_approval.' This names an alternative tool (claude_approval) and clarifies a key restriction, giving clear usage guidance.

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