Open Url

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

No annotations are provided, so the description carries the full burden: it does not say that this brings an app to the foreground, what happens if no handler exists for the scheme, whether it fails on an unknown package, or which device is targeted when 'device' is omitted. The scheme list and the package-override effect are the only behavioral facts supplied.

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?

Two sentences, front-loaded with the action, with the optional behavior in a parenthetical. No filler; the only nit is the awkward line break mid-sentence, which is cosmetic.

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?

An output schema exists, so return values need not be explained, and the URL/package semantics are covered. However, for a three-parameter device-action tool with no annotations, the unexplained 'device' parameter and the absence of any failure/foreground behavior leave meaningful gaps.

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 description coverage is 0%, so the description must compensate. It usefully explains the accepted URL schemes and clarifies that 'package' forces a specific app package (with an example), but the third parameter, 'device', is never mentioned — the agent cannot tell whether it takes a serial, an id, or a name, nor what the null default means.

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 and resource ('Open a URL ... on the device') and enumerates the accepted schemes (http/https/market), which goes beyond restating the name. It does not differentiate from plausible siblings like launch_app or send_intent, so an agent must infer which one to reach for.

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 only guidance is tied to a parameter ('optionally forcing it into a specific app package, e.g. open a link in Chrome'), not to tool selection. There is no statement of when to use open_url versus launch_app, send_intent, or when a package override is required versus optional.

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