iOS Simulator: Diagnostics

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

Beyond the readOnlyHint annotation, the description adds meaningful behavioral context: it reports 'both lanes separately', 'never fail[s]', and can detect a second runner by identifying which simulator owns the WDA port. This gives the agent useful expectations about reliability and output structure without contradicting the annotation.

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 dense but efficient, front-loading the core behavior ('Report both lanes separately and never fail') before enumerating the diagnostic contents. The later clauses about catching a second runner are slightly wordy but still earn their place by clarifying a key diagnostic use case.

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?

With no output schema, the description compensates by enumerating the major output categories: existing/usable simulators, the server-selected simulator, screen geometry, and WDA port ownership. This is enough for an agent to know what to expect, though exact output formatting remains unspecified.

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 provides full coverage for the optional 'device' parameter, including guidance on omitting it and the distinction from simctl's 'booted'. The tool description itself adds no parameter-specific detail, so the high schema coverage establishes the baseline.

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 a specific action ('Report') and a concrete diagnostic resource: simulator existence/usability, server-chosen simulator, screen geometry, and WDA status with port ownership. This distinguishes it from sibling tools like ios_simulator_list or ios_simulator_restart_wda by emphasizing an aggregated diagnostic report.

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 phrase 'Start here when anything else misbehaves' provides explicit situational guidance for when to invoke this tool. It does not spell out exclusions or contrast itself against specific sibling tools, but the context is clear enough for an agent to select it as a first-line diagnostic.

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