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Codex Android MCP

Android tap Row

android_tap_row
Destructive

Tap a relative position inside a list row to activate controls lacking identifiers, with counter-based verification to confirm the action.

Instructions

Tap at a RELATIVE position inside one visible list row reported by android_ui_rows: a 0-based row index plus x/y as fractions of that row's frame (0 = left/top edge, 1 = right/bottom, default 0.5 = row center). This is the list-app way to reach per-item controls that are NOT identifiable elements — an icon-only like or bookmark button inside the row subtree, commonly an ImageView with no resource-id and no content-desc. The row frame comes from a FRESH dump, so no absolute screen coordinate is ever guessed or remembered. Safety gate: the row is re-located in the current hierarchy and an out-of-range index FAILS (it never clamps to the last row); a tap on a real phone has real consequences (likes, posts, purchases), so with expect_count={key,delta} the tool verifies the action by re-reading the row label after ~800 ms and checking the counter moved exactly delta (+1 or -1) — and if the key is not among the row's parsed counters the tap is REFUSED before it happens (never probe a control to discover what it does). Without expect_count the tap still happens (an explicit row-relative position IS the identification) but nothing is verified — prefer expect_count whenever the row label carries counters. The verified count change is the confirmation: do not screenshot-and-compare pixels.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
xNoHorizontal position inside the row frame as a fraction 0..1 (0 = left edge, 1 = right edge). Default 0.5 (center). A right-side action button is often near 0.9.
yNoVertical position inside the row frame as a fraction 0..1 (0 = top, 1 = bottom). Default 0.5 (center).
rowYes0-based row index exactly as reported by android_ui_rows. Out-of-range FAILS — re-run android_ui_rows, never tap a remembered position.
serialNoTarget device serial from android_devices. Defaults to the currently streamed device, else the only connected one.
expect_countNoVerify the action by the target counter moving exactly delta: {key: "<counter key from android_ui_rows.counts>", delta: +1 | -1}. After the tap the row label is re-read and the check is reported as countCheck.verified — the only reliable confirmation a list app offers. The tap is REFUSED before it happens when key is not among the row's parsed counters (an unidentifiable control is never probed).
Behavior5/5

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

The annotations already flag destructive/non-idempotent behavior, but the description adds substantial context: the safety gate with out-of-range failure, the ~800ms verification delay, the refusal when the counter key is absent, and the explicit 'do not screenshot-and-compare pixels'. It discloses real consequences and verification semantics well beyond the structured metadata.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is fairly long but every section serves a purpose: purpose, usage, safety, verification, and anti-screenshot guidance. It is front-loaded with the main capability and then layers details logically. While not terse, the length is justified by the tool's complexity and the need to convey safety-critical behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 5-parameter tool with a nested object and no output schema, the description covers all essential aspects: the coordinate system, the row index handling, the serial parameter, expect_count's semantics and failure modes, and the meaning of the verification result. An agent has everything needed to call it correctly and interpret outcomes.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers all parameters with descriptions, giving a baseline of 3. The description adds value by clarifying the meaning of x/y fractions relative to the row frame, the semantics of row index (exact match, fail on out-of-range), and the detailed behavior of expect_count including the refusal logic and countCheck.verified result. It enhances comprehension without redundancy.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('tap') and resource ('one visible list row reported by android_ui_rows') and precisely defines the input as a 0-based row index plus fractional coordinates. It explicitly contrasts with identifiable-element tools, making its purpose unambiguous and distinct from siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly states when to use this tool: to reach per-item controls that are NOT identifiable elements, contrasting with element-based tapping. It also advises preferring expect_count whenever counters exist, and explains that without it the tap still works but is unverified. This gives actionable selection criteria and a strong recommendation.

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

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