set_volume

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

With no annotations, the description carries the full burden and does well: it discloses that the operation works by emitting button presses (a real side effect on device volume), that it verifies each step against the system volume indicator (implying a multi-step, non-instant operation), and that the achieved level is quantized to 1/16 on iOS. It stops short of stating failure modes or whether the device must be unlocked/foregrounded.

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?

Three tight sentences: what it does, how it does it with its precision caveat, and what it returns. Front-loaded with the action and no 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 two-parameter tool with no output schema, the description covers the return value ('final level') and the precision limitation, which are the two things an agent most needs. Remaining gaps — behavior when the target can't be reached exactly, and any device-state prerequisites — are minor.

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 coverage is 100%, so the baseline is 3, but the description adds real information beyond the schema: the schema presents 'level' as a continuous 0–1 number while the description reveals it is effectively quantized to 1/16 steps. That changes how an agent should choose and interpret the value.

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 ('Set the device's media volume') and goes further by naming the mechanism (volume button presses) and the verification method. An agent can tell this apart from the sibling press_button tool, which is a raw input primitive, 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?

Usage is implied by the mechanism description — this is the high-level way to reach a target volume rather than pressing buttons manually — but there is no explicit when/when-not statement and press_button is never named as the alternative for cases where this approximation isn't good enough. The context is inferable but not stated.

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