open_browser

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

With no annotations, the description carries the full burden. It discloses that Chrome connects to an existing window if debug port is active, otherwise returns a helpful message, and that Firefox imports cookies read-only. However, Edge behavior is not described, leaving a transparency gap.

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 front-loaded with a clear one-line purpose and uses sections for readability. It is somewhat lengthy with decorative dividers, but every section contributes useful information about browser behavior and overrides.

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?

While parameter semantics are strong, the description omits Edge-specific behavior despite listing 'edge' as a valid browser, and it doesn't clarify whether Chrome falls back to a fresh Playwright session when the debug port is unavailable. The output schema exists, so return values need not be explained, but these gaps prevent full contextual completeness.

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 0%, but the description adds full semantic meaning for every parameter in the Args section, including defaults (headless=False, cdp_url=localhost:9222) and special values (browser options, profile_path='auto'). This far exceeds the schema's bare structure.

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 opens with 'Open a browser for automation,' a specific verb+resource statement. It clearly explains browser types and distinguishes itself from siblings like navigate and close_browser by focusing on the browser lifecycle and connection behavior.

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 provides thorough context on when to use different modes: CDP for Chrome, fresh Playwright for Firefox, and manual overrides for custom profiles and CDP URLs. It does not explicitly exclude alternatives like setup_browser, but the usage context is clear.

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