browser_tab_new

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

Annotations cover safety (readOnlyHint=false, openWorldHint=true, destructiveHint=false), and the description adds a genuinely useful behavioral fact beyond them: the new tab becomes 'the connected tab,' i.e. it changes the active/connected session context. It omits any note about existing tab state or popup/blocker behavior, hence not a 5.

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?

A single front-loaded sentence that carries the action, the optional parameter, and the state-changing consequence with zero filler.

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 one-parameter tab-creation tool with full schema coverage and annotations carrying the safety profile, the description is essentially complete; only a pointer to the navigate/tab_select alternatives is missing.

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% and the schema already documents the URL parameter and its about:blank default. The description merely restates that the URL is optional, adding no format or syntax detail beyond the schema. Baseline 3.

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?

States a specific verb+resource ('Open a new tab') and adds a meaningful scope detail (optional URL, becomes the connected tab). It distinguishes the create-and-activate behavior from browser_tab_select, though it doesn't explicitly contrast with browser_navigate.

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?

No guidance on when to use this versus browser_navigate (navigate the current tab) or browser_tab_select/tab_list. The word 'optionally' hints at the parameter's optionality but gives no selector conditions or alternatives.

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