open_session

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

With no annotations provided, the description carries full burden. It discloses persistence, idle timeout, shared vs. isolated context, and the need to close. It does not mention potential side effects like display requirement for headed mode (described in schema) or rate limits, but overall provides good behavioral context.

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 four sentences, front-loaded with the primary action and return value. Every sentence adds essential information: purpose, persistence, parameter guidance, and cleanup. No redundant or filler content.

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's complexity (session management) and no output schema, the description covers key aspects: return format, persistence, sharing, headed mode, timeout, and cleanup. It does not detail post-session navigation or log retrieval, but these are covered by sibling tools. It is sufficiently complete for an agent to understand and use correctly.

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%, so baseline is 3. The description adds value by explaining the effect of 'project' (shared authenticated context) and 'headed' (visible window), which enriches the schema's basic descriptions. 'url' is straightforward, but the added context justifies a 4.

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 uses a specific verb ('Open') and resource ('persistent browser session') and clearly states the return values. It distinguishes from sibling tools by emphasizing that the page stays alive for multi-step workflows, which is unique among the sibling list (e.g., close_session, navigate_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 provides clear context: use for multi-step workflows, pass 'project' for shared authenticated context, use 'headed' for visible windows, and close_session when done. It implies when to use but does not explicitly state when not to use or name alternatives, though the sibling tools cover single-step actions.

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