list_devices

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

With no annotations, the description must carry the whole burden; 'List' conveys read-only and 'known to this Mac' hints at local tooling scope, and it discloses that connection state and the default marker are returned. It omits what happens when no devices are connected and gives no indication of the discovery mechanism or failure modes.

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?

Two short sentences, front-loaded with the verb and resource. The second sentence ('The device tools use by default is marked') is grammatically awkward and slightly slows parsing, but nothing is redundant.

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?

There is no output schema, so the description has to convey the return value; it names connection state and the default marker but not the device identifier format or ordering, which an agent needs when chaining into select_device. Adequate but with a visible gap.

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 tool takes zero parameters, so the baseline is 4. There is nothing for the description to disambiguate, and it correctly adds no parameter prose.

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 ('List physical iPhones/iPads known to this Mac') plus the extra payload ('with connection state'), which distinguishes it from list_apps and the app-manipulation siblings. It falls short of 5 only because it doesn't explicitly contrast with select_device, the closest conceptual sibling.

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 mention of a default-marked device implies a discovery-then-select workflow, so an agent can infer this is the entry point before calling select_device. But no explicit when-to-use, prerequisites, or named alternative is given.

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