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 does well: it discloses idempotency ('Safe to call twice — it reuses the session that is already open'), the headed/single-session nature, and human takeover semantics. It omits failure modes (e.g., what happens if Chrome cannot launch) and any auth or timing behavior.

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: action and return value first, then human-facing usage, then idempotency. Every sentence carries distinct information with 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 zero-parameter tool with no output schema, the description adequately covers the return value (live view URL), idempotency, and human cooperation model. It could be slightly more complete by stating that this must be opened before the other browser_* tools can drive the session.

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?

There are zero parameters with 100% schema coverage, so the baseline is 4. The description correctly adds no parameter detail because none is needed, though it does not mention a configurable session name or similar implied knobs.

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 — starting the single headed Chrome session and returning the live view URL — and the phrase 'the one headed Chrome session' plus 'reuses the session that is already open' carves out its singleton role versus siblings like browser_close and browser_status. An agent immediately knows this is the session entry point.

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?

It gives clear operational context: the returned URL goes to the human, who can watch or take over while the agent drives, and it is safe to call twice. It never explicitly says when not to call it or names a sibling alternative, so it falls short of a 5.

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