ios_observe

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

With readOnlyHint=true already covering the safety profile, the description adds useful behavioral context: it explains the numbered output, screenshot inclusion, annotation behavior, and the important coordinate mapping that pixel equals tap coordinate. It does not cover failure behavior when no booted device exists or multiple devices are ambiguous, but it is substantially informative.

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 front-loaded with the core purpose, followed by compact parameter notes under "Args:". Every sentence adds operational value with no redundant 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 three-parameter observation tool with no output schema, the description explains what is returned, how the screenshot relates to tap coordinates, what annotation does, and how device selection defaults. Nothing essential for correct invocation is missing.

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 0%, so the description must carry parameter meaning, and it does: screenshot controls screenshot inclusion, annotate controls index drawing, and device accepts a simulator name or UDID with a clear default. The screenshot explanation also adds the critical scaling/coordinate detail not present in the 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?

States a specific verb and resource: "See the screen," and immediately specifies the return shape as a numbered element list plus screenshot. This clearly distinguishes observation from action-oriented siblings such as ios_tap, ios_swipe, and ios_type.

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 observation purpose is implied by "See the screen," so an agent can infer this is the inspection step before interacting. However, the description does not explicitly say when to use it versus alternatives or mention prerequisites such as needing a booted simulator.

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