app_current

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

Annotations provide readOnlyHint=true and openWorldHint=true, and the description aligns with them (no contradiction). The description adds specificity about what is returned (package name and activity), which is the key behavioral output an agent needs. The openWorldHint meaning is somewhat ambiguous but not contradicted by the text.

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 description is a single efficient sentence that fully states the tool's purpose and return value. Zero wasted words, perfectly front-loaded.

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?

This is a simple read operation with good annotations, a single fully-documented parameter, and an output schema present. The description adequately covers what the tool does and returns. For such a low-complexity tool, coverage is sufficient; slightly more context about format of the output (e.g., 'com.example.app/ActivityName') could help but the output schema mitigates this.

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 100% — the single 'serial' parameter is fully documented in the schema as 'Device serial number'. The description doesn't add parameter-specific detail beyond what the schema provides, so baseline 3 is appropriate.

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 is specific: 'Get the currently foregrounded app package name and activity.' It uses a clear verb ('get') with a precise resource (foregrounded app) and states the exact return values (package name and activity). While siblings exist (app_list, app_start), the read-only 'current app' purpose is distinct enough from those.

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 implies a query context (foreground status inspection) but provides no explicit when-to-use guidance versus alternatives like app_list or ui_get_state. No exclusions or alternative tool references are given. It's clear enough for straightforward use but lacks explicit differentiation.

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