native_open

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

Beyond annotations (openWorldHint, idempotentHint), the description discloses that it returns 'ok:false with a reason if the device/tooling isn't ready', that JS and native logs stream to the timeline, and that browser_* tools drive the native app via idb/adb. No contradiction.

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 a single paragraph with multiple sentences, packing necessary information efficiently. It is front-loaded with the core action. While not overly terse, it earns its sentences.

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 no output schema, the description covers return behavior, prerequisites, sibling relationship, and lifecycle (build first, close after). The annotations provide additional context, making it complete for an agent to decide when to use.

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 coverage is 100% with enum description. The description adds context by stating the platform values ('ios (simulator) or android (emulator mirror)') and tying to the active pane, reinforcing the schema. No additional param semantics needed beyond schema.

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 verb 'Open' and the resource 'native target for the active pane (Expo/React Native): the iOS simulator or the Android device mirror'. It distinguishes from browser_* tools which drive web pages, and notes that browser_* tools can then drive the native app, providing clear purpose.

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 prerequisites ('Cockpit-only (needs the Electron app + a booted simulator/emulator)'), instructs to build first with 'native_build' and close with 'native_close'. It also implies usage context by differentiating from browser_* tools.

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