open_url

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

With no annotations available, the description carries the disclosure burden; it does state the core side effect (opening a URL/deep link on the phone). It does not disclose failure/foreground behavior, potential app-switching, or other consequences, and the wait-for-foreground trait is only present in the schema rather than in the description.

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 short, front-loaded with the action, and contains no filler. The Args block is slightly redundant with the schema and incompletely lists the optional parameter, so it is not perfectly polished.

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 simple two-parameter tool with an output schema, the description plus schema is largely sufficient: it covers the required URL parameter and accepted formats, while wait_seconds is documented in the schema. It could be more complete with explicit alternative routing, but an agent generally has enough to call the tool correctly.

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 complete, so the baseline is 3, but the description adds tel: and sms: deep-link examples that go beyond the schema's geo: example. It does not mention wait_seconds in its Args block, though the schema already documents that parameter clearly.

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 states a specific verb ('Open') and a clear resource ('a web address or deep link'), and the tel:/sms:/geo: examples make the intended scope concrete. This differentiates it from sibling open_app, which is about launching an app rather than resolving a URL/deep link.

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 use case is implied by the name and by the phrase 'web address or deep link', but the description never explicitly compares this tool to open_app or says when not to use it. There are no exclusions or routing hints beyond the action itself.

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