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

Goes well beyond the annotations by disclosing that selecting usually opens an item, that the call returns the new state with the next snapshotId so no extra snapshot is needed, that a changed window causes a no-op with a retryable error carrying current state, and that a 'sent' action is not proof of success. It also states the ui and process permission requirement. This is rich behavioral context the structured fields do not carry.

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?

Front-loads the core action and then layers behavioral details, with almost no filler. It is somewhat dense at five clauses, but each sentence carries distinct operational value rather than restating the name.

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?

Despite having no output schema, the description explains the return value (the app's new state plus next snapshotId), the error/retry behavior, and the permission requirement. Nothing an agent needs to invoke this correctly appears to be missing.

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 only 50% (elementId and snapshotId are undocumented in the schema), so the description should compensate more than it does. It implicitly maps 'row, tab or list item' to elementId and references the latest snapshot for snapshotId, but adds no format or constraint detail beyond that. Adequate but thin against the coverage gap.

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 (select) and resource (a row, tab, or list item of the latest app_snapshot), and adds the important effect that selecting a row usually opens it. An agent can distinguish this from siblings like app_press, app_snapshot, or browser_select without opening their schemas.

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 ties usage to 'the latest app_snapshot,' implying a snapshot must exist first, which is useful context. However, it never explicitly states when to prefer this over app_press, app_show_menu, or browser_select, nor any exclusion conditions, leaving the routing decision largely to inference.

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