browser_session_start

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

With no annotations provided, the description fully discloses behavioral traits: session scoping, new window vs. tab group, focus management (brings to front once, no focus steal on navigate), and idempotency. No contradictions.

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 (5-6 sentences), front-loaded with the core purpose, and each sentence adds distinct value (scoping, newWindow, focus, idempotency). No redundant or vague phrasing.

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?

For a complex tool with 11 parameters, nested objects, and no output schema or annotations, the description covers key behavioral context (session management, focus, new window) but omits explanations for most parameters (e.g., dimensions, position, state, visuals). The agent would need to infer parameter meanings from schema defaults/enums alone.

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 only 18% (9 of 11 parameters lack descriptions in schema). The tool description only explains newWindow and bringToFront behaviour, leaving parameters like title, color, width, height, left, top, state, and the entire visuals nested object unaddressed. This is insufficient for an 11-parameter tool.

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 new browser session' and specifies the resource ('Chrome tab group with an initial tab; all subsequent operations are scoped to that group'). It distinguishes itself from siblings like browser_open_tab by focusing on session initiation and scoping.

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 explicit guidance on when to use parameters like newWindow and bringToFront, and notes idempotent behavior (ends previous session). However, it does not explicitly compare to alternative tools or state when not to use it beyond the implied 'start a new session' context.

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