update_device_settings

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

Annotations already declare a non-read-only, open-world, destructive operation, and the description adds meaningful context beyond them: the exact field-level blast radius and the existence of a confirmation requirement for the target. It does not explain reversibility or what confirmation looks like, and the narrow 'display unit' framing sits somewhat awkwardly with destructiveHint=true without reconciling it.

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 sentences, no filler, with the positive scope stated first and the exclusion list immediately after. Every clause carries information an agent needs before calling.

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 mutation tool with no output schema, the definition covers what changes, what doesn't, value formats, and the confirmation precondition. It omits any indication of success/failure signal or whether omitted fields are preserved, leaving a small 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 carries the burden and does so well: it specifies the accepted values for display_unit (f/c) and the format for time_zone (IANA) and clarifies that target must be a confirmed device. It remains silent on defaults/null behavior, which the schema only hints at.

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 names a specific mutation verb ('Change') and precisely bounds the resource to display_unit and device time_zone on a confirmed target. The explicit statement that it does not change power or target temperature cleanly separates it from siblings set_power, set_temperature, and update_routine.

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?

'For a confirmed target' establishes a prerequisite, and the negative scope ('Does not change power, target temperature, routine timezone, or reporting timezone') implicitly routes the agent to set_power, set_temperature, or update_routine for those needs. It stops short of naming those alternatives explicitly, so it is a strong 4 rather than a 5.

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