open_tab

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

No annotations are provided, so the description must cover behavioral aspects. It discloses that the tool waits for the page to finish loading, which is a significant behavioral trait, and explains that the final URL may differ due to redirects, adding valuable context. However, it doesn't mention potential side effects like affecting the tab list or requiring network permissions, which could be relevant but not essential.

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 concise and well-structured: the first line states the primary action, followed by usage guidance, then a note about the return value. Each sentence serves a purpose, and the argument documentation is minimal but adequate. No fluff or redundancy.

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?

With a single parameter, a clear output schema (returning tab handle and final URL), and no annotations, the description covers the essential use case and key behavior. It could go into more detail about error handling (e.g., invalid URLs) or if simultaneous tabs are supported, but for a tool of this simplicity, it is sufficiently complete for an agent to invoke 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 effectively 0% (no description in the schema), so the description must compensate. It explains that parentheses and spaces in the URL are encoded automatically, which goes beyond the schema's minimal type definition. It doesn't elaborate on the URL format (e.g., must be fully qualified), but the provided handling of special characters is useful and relevant.

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 the tool opens a URL in a new Safari tab and waits for loading, with a specific verb ('Open'), resource ('URL'), and context ('new Safari tab'). It also distinguishes itself from the sibling 'navigate' by noting that it preserves the user's current page, avoiding ambiguity.

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?

Explicitly advises to prefer this tool over 'navigate' when starting a task, citing the benefit of leaving the user's current reading untouched. This provides clear when-to-use guidance and names the alternative, leaving no inference needed.

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