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

Annotations only declare the mutation/idempotency profile (readOnlyHint=false, idempotentHint=false). The description adds real behavioral context beyond them: a 4-digit PIN appears on the TV's own screen, the call is a prerequisite for all other remote calls, and pairing persists across restarts. It stops short of describing failure modes (timeout, PIN rejection, re-pairing an already-paired TV).

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 sentences, each carrying distinct load: what it does, the PIN handoff, and the prerequisite/persistence constraint. The action and its sequencing constraint are front-loaded with 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 one-parameter stateful handshake step with no output schema, the description covers everything an agent needs: the trigger, the out-of-band PIN it must read, the tool that consumes that PIN, and the fact that pairing is a persistent prerequisite. No return-value explanation is needed since the meaningful output appears on the TV screen.

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 100% and the single parameter's accepted forms (UDID, name, or identifier from ios_tv_list) are documented in the schema itself. The description adds no further parameter semantics, so the baseline 3 applies.

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 ('Start pairing with an Apple TV') and immediately distinguishes itself from the sibling that completes the operation, ios_tv_pair_finish. An agent can tell this apart from ios_tv_button, ios_tv_status, etc. without opening any 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?

Explicitly states the precondition ('Pairing is required before any other remote call works') and the follow-up tool with its required input ('read it off the screen and pass it to ios_tv_pair_finish'). It also tells the agent this is a one-time step per TV, which directly informs when NOT to call it again.

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