set_input

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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses a precondition ('receiver must be on') and the label convention for source names, but says nothing about failure behavior, whether the change is idempotent, or side effects on other settings — gaps that matter for a state-changing call.

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 short sentences, front-loaded with the action, followed by the naming convention and the precondition. Every sentence adds information; there is 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?

An output schema exists, so return values need not be described, and the core action plus precondition are covered. It omits any mention of multi-zone behavior or the default-receiver fallback, though the schema itself documents the latter.

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 only 50% (the receiver parameter is documented in the schema, source is not). The description compensates for the undocumented parameter by explaining that values mirror front-panel labels and giving concrete examples ('bd-dvd', 'net'), which adds meaning the bare enum cannot convey.

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 gives a specific verb and resource ('Select the main zone's input source'), which is inherently distinct from sibling operations like set_volume, set_mute, or set_power. It does not explicitly name or contrast any sibling, so it stops short of the top tier, but an agent can identify the operation without opening the 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 context is clear (switch the main zone's input) and a concrete precondition is stated: 'The receiver must be on.' There is no explicit when-not guidance or reference to alternatives, but for a simple discrete setter the context is sufficient.

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