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

Annotations only give readOnlyHint=false and destructiveHint=false; the description goes well beyond by disclosing that get returning 0 and set failing are expected on tvOS 27 rather than faults, and that the call does not wake the TV because the key goes to whatever owns the volume. This is exactly the non-obvious behavior an agent needs.

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?

The core action and the recommended ops are front-loaded in the first two clauses, and each later sentence carries non-obvious diagnostic value. It is dense rather than padded, though the tvOS-27 measurement sentence is slightly verbose.

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 mutation tool with no output schema and full param coverage, the description covers everything needed: which ops work, why the others may report failure, and the power/wake side effect. No material gap remains for correct invocation.

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 meaning: it explains why `get`/`set` are unreliable, what the ops map to (remote keys vs absolute level), and how `level` is interpreted contextually. The enum semantics are enriched beyond the schema's one-line summaries.

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 first sentence names a specific verb and resource ('Change an Apple TV's volume'), and the surrounding siblings (ios_tv_button, ios_tv_power, ios_tv_swipe) make the volume scope unambiguous. An agent can distinguish this tool 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?

It explicitly directs the agent to `up`/`down` as 'the ones that work', explains that `get`/`set` target an absolute level a HDMI-connected TV does not own, and warns against building a level slider on `get`. That is concrete when-to-use and when-not-to-use guidance.

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