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

With no annotations, the description carries the full behavioral burden. It discloses that the report is base64-encoded, its byte-length must exactly match reportLen from CREATE time, and it is a generic raw-report primitive that is not text-aware. It could add failure/return behavior, but the critical constraints are clearly surfaced.

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 description is about four sentences and front-loads the action and main constraint before the alternative. It is slightly repetitive with 'previously created' and the device_uhid_create reference, but it has no real 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 3-parameter primitive with no output schema, the description covers the prerequisite, the key byte-length constraint, and the preferred alternative. It does not document response or error behavior, but that is a minor gap given the low complexity and absence of an output schema.

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. The description adds meaning beyond the schema by connecting reportBase64 to the exact byte-length requirement from CREATE and explaining that the tool is a raw primitive for composing reports, which clarifies how the parameters relate to each other.

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 states a specific verb ('Send') and resource ('HID input report to a previously created UHID device'), then clarifies it is a generic raw-report primitive for any UHID device and is not text-aware. This clearly distinguishes it from device_type and the higher-level UHID helpers.

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 says to prefer device_type for typing a string and to use this tool only when composing exact reports yourself, while also referencing device_uhid_create as a prerequisite. This gives the agent an explicit when-to-use/when-not-to-use decision.

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