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

Annotations already declare the safe, idempotent, non-destructive, closed-world read profile. Beyond that the description adds genuine behavioral detail: prerequisites (no session, no foregrounding), the return shape (UTF-8 text or empty string), and a version/environment failure mode ('no HID available' on iOS 17.x / no-tunnel). Only the error/limitation behavior is spelled out, not retry or rate considerations, keeping it short of a 5.

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 short sentences with zero filler: mechanism first, then return value, then the failure caveat. Every sentence carries distinct information and nothing is repeated from the schema or annotations.

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?

With no output schema, the description correctly carries the return contract (UTF-8 text, empty string, 'no HID available' failure), and it discloses prerequisites and an OS-version limitation. For a one-parameter read tool this is nearly complete; the only gap is the unresolved overlap with ios_get_pasteboard.

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?

There is a single parameter (udid) with 100% schema description coverage, so the schema already documents it fully. The description adds no syntax, format, or sourcing detail for udid, so the baseline of 3 for schema-covered parameters 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 and resource ('Read the device clipboard (pasteboard) via the system clipboard service'), so the operation is unambiguous. It does not, however, distinguish itself from the closely-named sibling ios_get_pasteboard (or device_clipboard_get), which an agent would have to guess between.

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 supplies enabling context ('no automation session needed, no app foregrounding'), which implies the tool is usable without a session. But it never states when to prefer this over ios_get_pasteboard or ios_clipboard_set_hid, leaving the alternative-selection inference to the caller.

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