session_start

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

With no annotations, the description must carry behavioral disclosure. It discloses that a fresh tab is opened and that recording starts, which is useful. However, it does not explain state resets (e.g., if a session already exists), navigation behavior for the optional URL, or any return values or session identifiers.

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 a single sentence that is front-loaded with the primary action ('Open a fresh browser tab') and has no filler or redundant phrases. It earns its place entirely.

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 core action is covered, but the tool has no output schema and no annotations, so the description should explain what happens after starting (e.g., whether a session ID is returned, how the session continues). The relationship to sibling tools is also omitted, which is important for an orchestration flow.

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 100% because both parameters have descriptions, so the baseline is 3. The description adds only a minor hint that the goal is central by calling the session 'goal-driven', but it does not provide additional semantic detail beyond the schema.

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 and resource: 'Open a fresh browser tab and start recording a goal-driven session.' This clearly identifies the tool as the session initializer, distinguishing it from siblings like session_act and session_observe.

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 usage when starting a new session, but it does not explicitly state when to use this tool versus alternatives, nor does it mention any preconditions or that subsequent tools (session_act, session_observe) should follow. Guidance is only implicit.

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