playwright_start

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

With no annotations, the description carries the burden of disclosing behavior. It reveals that the session is persistent, always records traffic, archives to the web-archive store in real time, and returns a confirmation. It does not mention potential edge cases like existing sessions, but for a simple start action this is reasonably transparent.

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 three short sentences with no redundant information. The first sentence states the core action, the second provides a key behavioral detail, and the third mentions the return value. Every sentence earns its place.

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?

The tool is simple (no params, start command), and the description covers its main behavior and side effect (archiving). An output schema exists, so return values don't need explanation. It could be slightly more complete by explicitly stating it's a prerequisite for other playwright tools, but it's sufficient for the given context.

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?

The tool has zero parameters, and the schema has no properties. Per the rubric, 0 params gives a baseline of 4. The description adds context about what the session does and its archiving behavior, which is meaningful even without parameter-specific details.

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 a specific action ('Start') and a specific resource ('persistent interactive Playwright session'), while also distinguishing itself from sibling tools by mentioning the always-on traffic recording aspect. It's unambiguous what this tool does compared to other playwright_* and archive_* tools.

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 description implies that this tool is the entry point for a persistent Playwright session, but it doesn't explicitly say when to use it vs. alternatives like playwright_record or playwright_navigate. There's no explicit 'use this before other playwright commands' or exclusions, so guidance is only implied.

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