ios_set_value

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

Annotations already indicate the tool is destructive and not read-only, and the description adds meaningful behavioral context beyond those annotations: it checks the current state before acting and avoids an unintended toggle. This is valuable non-obvious behavior that helps the agent predict outcomes, though it does not elaborate on broader side effects.

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 only two sentences: the first states the purpose, and the second explains the key behavioral advantage. Every sentence earns its place, and the most important guidance is front-loaded.

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?

Given the annotations, full schema coverage, and output schema, the description provides sufficient context for correct invocation. It clearly identifies the supported control types and the state-checking behavior. A small gap is that it does not explicitly mention when tapping might still be the better choice, but that is a minor omission and partially covered by the usage guidance.

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 100%, so the schema already documents the parameters. The description mainly reiterates the 'value' concept without adding new parameter-level detail; it does not need to compensate because the schema is complete.

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 uses a specific verb ('Set') and explicitly lists the target resource types ('switch, slider, stepper, or picker'), making it immediately clear what the tool does. It also distinguishes itself from the tap alternative by explaining why it is preferred for switches.

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 directly advises preferring this tool over tapping a switch and explains the behavioral reason: it checks current state first, so asking for 'on' when already on results in no action. This gives the agent a clear decision rule for when to choose this tool over its sibling, ios_tap.

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