Open pane

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 that `command` alone runs through the shell while `args` executes directly with exact argv, warns about shell mangling, describes `meta` reserved keys, and explains project recency bumping and precedence. This goes beyond the schema and provides meaningful behavioral context, though some side effects of other parameters remain implicit.

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 long but densely packed with necessary information. It is front-loaded with the core function, then dives into parameter nuances. Every sentence earns its place, though the parenthetical asides make it slightly harder to skim.

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 10 parameters, no annotations, and no output schema, the description is quite complete. It covers return value, default window, parameter behavior, and failure cases for project. Some interactions (e.g., env merging, label limits) are not mentioned, but overall it addresses the complexity well.

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 20%, but the description compensates richly. It explains the critical command/args relationship, the reserved keys for meta, and the project parameter's effects (cwd, color, recency, precedence, failure on unknown handle). This adds substantial meaning to parameters that the schema leaves opaque.

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 opens a new pane in the active tab of a window, defaults to the first window, and returns the new paneId. This specific verb+resource and its distinction from sibling tools like open_tab and focus_pane make the purpose unambiguous.

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 provides explicit guidance on when to use `command` alone versus `args` (when arguments contain spaces or quotes) and references related tools list_projects/add_project for project handling. It does not explicitly contrast with open_tab or other pane operations, but the parameter-level usage conditions are clearly stated.

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