Open App Link

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

Annotations indicate readOnlyHint=false and openWorldHint=true, meaning it mutates state and interacts with the external world. The description adds transparency by stating it verifies the foreground state and blocks unknown/dangerous schemes unless explicitly allowed. It doesn't describe failure behavior (e.g., what happens if verification times out), but the added safety and verification context is valuable beyond 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?

The description is a single, focused sentence that front-loads the core action and outcome. It includes essential details (binding, safety) without waste. The structure is clean and easily scannable.

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?

Given the tool's complexity (5 parameters, nested waitFor object, no output schema), the description covers the primary purpose, binding guidance, and safety rules. It doesn't explain return values or failure scenarios, but these are not explicitly required given the tool's nature and the presence of annotations. It is sufficiently complete for an agent to decide when and how to use it.

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% with all parameters described. The description adds extra meaning by explaining that packageName and appName are used to bind the expected destination, and that waitFor represents readiness conditions after routing. It goes beyond the schema descriptions by providing context on how parameters relate to the tool's purpose.

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 clearly states a specific action (open a URL or deep link) and a verification outcome (confirm the requested app becomes foreground). It distinguishes itself from siblings like mobile_open_url (which likely just opens) and mobile_launch_app (which launches without URL routing) by mentioning the binding mechanism and the foreground verification.

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 provides concrete usage guidance: how to bind the expected destination via packageName or appName, and the safety condition requiring MOBILEMCP_ALLOW_UNSAFE_URLS=1 for unsafe schemes. It implies this tool is for cases where you need to verify the app becomes foreground, but it doesn't explicitly contrast with sibling tools like mobile_open_url or mobile_launch_app, so it's clear but not exhaustive.

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