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

With no annotations present, the description carries the full burden of behavioral disclosure. It reveals that no automation session or app foregrounding is required and explicitly states the 'no HID available' error on iOS 17.x/no-tunnel. This is meaningful behavioral transparency beyond the schema.

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?

Two sentences with no wasted words: the first front-loads action, mechanism, and key constraints; the second captures the relevant platform limitation. Very efficient and well structured.

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 simple two-parameter write tool with no output schema, the description adequately covers purpose, mechanism, usage context, and a notable failure mode. It does not mention the success return value or explicitly distinguish sibling clipboard tools, but these are minor gaps for a tool this straightforward.

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%, with both parameters already described ('Text to place on the device clipboard', 'iOS device UDID'). The description adds no additional parameter-specific meaning, so the baseline score of 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?

The description clearly states the action ('Write the device clipboard') and the resource ('pasteboard'), and adds a distinguishing mechanism ('via the system clipboard service') plus the absence of session/app foregrounding requirements. It does not explicitly name sibling alternatives, but the function is unmistakable.

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?

The description gives clear context for when this tool is appropriate: when clipboard writes should occur without an automation session or app foregrounding. It also discloses a platform-specific failure condition. It does not explicitly contrast with sibling clipboard tools like ios_set_pasteboard or device_clipboard_set, but usage context is well implied.

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