ACTION_MINI_SCREEN

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

With no annotations supplied, the description carries the full burden and does substantial work: it declares non-blocking behavior, the permission prerequisite, that output is returned as the variables mini_screen_success/mini_screen_shown/mini_screen_error, and — importantly — that once a user dismisses the overlay during the run, later writes only update content and do not re-pop (mini_screen_shown=false). It also notes the source label cannot be set via parameters. What it omits is whether concurrent invocations create multiple overlays and any cost/rate implications of repeated writes.

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 structure is front-loaded and logical: purpose and prerequisite, then output variables, then input constraints, then behavioral traits. Sentences are dense but each carries information; the parenthetical prerequisites and the trailing interpolation note are slightly compressed but nothing is redundant.

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 10-parameter, zero-required, no-output-schema tool, the description covers the essentials an agent needs: what it renders, permission gating, non-blocking semantics, the minimum-content rule, dismissal persistence, and the names of the result variables. The main remaining gap is interaction with the mini_screen_status sibling and any multi-overlay behavior, which matters given the tool's UI side effects.

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 already 100%, so the baseline would be 3; the description adds real meaning beyond it by stating the cross-parameter rule that show/append requires at least one of text, image, title, or progress — a constraint the schema does not encode since zero parameters are marked required. It also documents ${var} interpolation across string parameters and that results come back as a variable snapshot JSON, both of which are semantic additions rather than restatements.

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 opens with a specific resource and capability: a floating mini-screen that shows text, images, and progress to the user in real time. It is clear enough to distinguish from most siblings, but it never names mini_screen_status (the natural query counterpart) or explains how it differs from ACTION_TOAST or ACTION_SEND_NOTIFICATION, so the differentiation is left implicit.

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?

Usage is implied by 'show text/images/progress to the user in real time' plus the stated prerequisite (Habitat accessibility service or overlay permission), which is genuinely useful context. However, there is no explicit when-to-use vs. when-not guidance and no routing to mini_screen_status for reading current state, leaving the agent to infer the boundary.

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