open_session

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

Without annotations, the description carries the full burden. It discloses that URL policy is enforced before returning the session and that the tool reports the landing page. However, it lacks additional context about resource cleanup or failure modes beyond URL refusal.

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?

Two sentences, no filler. The first sentence states the action and result; the second adds a key behavioral constraint. Every word 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?

Given the tool's simplicity and the presence of an output schema, the description covers the main purpose and a key policy. However, it doesn't explain session lifecycle expectations (e.g., that close_session is needed), but this is a minor gap.

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 input schema provides only the property name 'url' with no description, and schema description coverage is 0%. The description merely restates the concept of opening a URL without adding format constraints, accepted schemes, or examples, so it does not compensate for the missing schema detail.

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 the specific verb 'Open' with the resource 'browser session' and URL, and explains the reporting behavior. It clearly differentiates from sibling tools like close_session and inspect_page by describing the opening action.

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 clearly indicates this tool is used to start a browser session at a given URL, implying the entry point before other operations. It doesn't explicitly mention alternatives or exclusions, but the context is unambiguous given sibling tools.

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