browser_open

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

With no annotations, the description carries the full burden, and it does disclose one meaningful trait: it targets a browser the user is watching and opens a new tab if none is shared. It omits whether this is headless or visible, whether it waits for load, and what happens on failure, which matters for an operation with side effects in a shared session.

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?

Three tight sentences, front-loaded with the action and scoping, followed by the alternative-selection rule and the tab fallback. No filler.

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 one-parameter navigation tool with no output schema, the description covers the essentials plus the shared-session and new-tab behavior. It falls short only on distinguishing itself from the near-identical browser_navigate sibling.

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 100% and there is a single required parameter, so the schema already documents the URL format. The description's 'website or localhost app' adds only a mild hint about accepted targets, so the baseline of 3 applies.

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 ... in the browser inside VS Code') and clarifies scope with 'website or localhost app'. It does not, however, differentiate itself from the very similarly named sibling browser_navigate, which is the reader's most likely confusion.

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 gives a use condition ('whenever the user wants a page opened, viewed, tested, or clicked through') and names an alternative (WebFetch) to prefer this over. The gap is that the closest sibling, browser_navigate, is never addressed, so sibling selection remains ambiguous.

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