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

With only readOnlyHint and openWorldHint in annotations, the description carries substantial extra context: the exact return signal on failure ('timed_out after timeout_seconds'), the max-50 cap, the retry pattern, and an explicit prompt-injection warning that device/metric names are attacker-controlled and must never be treated as instructions. This is behavioral disclosure the annotations cannot provide.

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?

Four sentences, each load-bearing: semantics, usage trigger, timeout/retry behavior, security caveat. The core blocking behavior is front-loaded and nothing is padded.

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?

No output schema exists, yet the description tells the agent what it gets back (a reading, or a timed_out signal) and what to do on timeout. Combined with the injection warning and timeout constraints, an agent has everything needed to call this correctly.

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?

At 67% schema coverage, the description adds real meaning: it defines 'new' precisely relative to the call moment and the optional 'after' unix time, and it pins timeout_seconds to a 50-second max with a timed_out outcome. The bare timeout_seconds schema entry is effectively documented by the prose, though the device naming rules are left to the schema.

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 with blocking semantics: 'Wait until a device sends a new reading, then return it.' The 'wait' framing cleanly separates it from siblings like get_latest and get_history, which an agent can distinguish 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?

Gives a concrete trigger scenario ('call this right after flashing or powering up a device to confirm it is actually posting') and the re-entry rule after timeout ('call again to keep waiting'). It never names a competing sibling such as get_latest or explains when *not* to block, so it stops short of a full when/alternative routing.

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