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

Annotations already declare the full safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=false), so the bar is low. The description does add one piece of context beyond them: that the call "releas[es] resources," telling the agent something is freed rather than merely flagged. It does not say what happens to in-flight automation or whether the device is left in a clean state, and nothing contradicts the annotations.

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?

A single front-loaded sentence with no filler. It loses a point for minor redundancy and awkwardness — "a iOS" and "on an iOS device" restates the resource already named in "iOS automation session."

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 lifecycle tool with 100% schema coverage and annotations carrying the safety profile, the description covers purpose and the resource-release effect. Remaining gaps (error behavior when no session exists, ordering relative to ios_start_session) are minor at this complexity.

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 there is only one parameter (udid), which the schema documents as "iOS device UDID." The description mentions the device but adds no syntax, format, or sourcing detail beyond the schema, 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 and resource ("End a iOS automation session"), so an agent knows exactly what it does. However it never references its natural counterpart ios_start_session or the other teardown siblings (session_quit, ios_release_hid, device_release), so sibling differentiation is absent.

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 no when-to-use guidance, no prerequisites, and no exclusions. With several other teardown tools in the sibling list (ios_release_hid, ios_release_contacts_hid, ios_record_cleanup, device_release), the agent gets no help deciding which teardown to call or in what order.

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