set_default_device

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

No annotations are provided, so the description carries the full burden. It discloses the key behavioral trait that this mutates session state persisting into later calls (overriding ADB_SERIAL) and defines the clearing semantics via empty string. It does not say whether the serial must be connected/valid or what error surfaces otherwise, but the core side effect is well disclosed.

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 tight sentences, no waste, with the primary effect front-loaded before the clearing rule. Every clause earns its place.

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?

An output schema exists, so return values need not be described. For a single-parameter session-mutating tool, the description covers purpose, persistent effect, and reversal; only validation/error behavior on a bad serial is unaddressed, which is a minor 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?

Schema description coverage is 0%, so the description must compensate, and it does: the lone parameter is identified as a device serial and the non-obvious sentinel value (empty string clears) is spelled out, which the bare 'string' schema does not convey. Serial format/validity is still left implicit.

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+resource ('set the session default device serial') and clarifies scope with the parenthetical that it overrides ADB_SERIAL for later calls. This cleanly distinguishes it from the sibling getter get_default_device without opening either schema.

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?

Implies the use case (route subsequent calls to a chosen device) and explains how to undo it ('pass an empty string to clear it'), but never names alternatives such as get_default_device or get_devices, nor states when setting a default is preferable to passing a serial per call. Usage is inferable rather than explicit.

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