start_session

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

The description indicates a session is started and navigation occurs, but with no annotations provided, it fails to disclose important behavioral details such as whether a previous session is terminated, authentication requirements, rate limits, or what the returned output contains.

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: one clear sentence followed by a compact parameter list. Every sentence adds value with no redundancy or 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?

Given the tool has an output schema (not shown), the description omits information about what the tool returns (e.g., session ID). No annotations are provided, and the parameter coverage is complete but behavioral context is missing for a session-starting tool.

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?

Despite a context signal of 0% schema description coverage, the description includes an Args block explaining each parameter: url is the test URL, headless controls visibility, viewport dimensions set size. This adds meaningful context beyond the schema's type and default values, especially for url which has no defaults.

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: 'Start a browser testing session and navigate to the given URL.' The verb 'start' and resource 'browser testing session' are specific, and the action includes navigation. This distinguishes it clearly from siblings like 'navigate' (which does not start a session) and 'end_session'.

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 this is the initial tool to call, as it starts a session and navigates. However, it provides no explicit guidance on when to use this tool versus alternatives like 'navigate' or 'crawl_site', nor does it mention prerequisites or caveats.

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