New tab

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

With no annotations, the description carries the full burden and does disclose two useful behaviors: the tool returns the new tab's ID, and tabs are per-agent within a shared slot to avoid interference. It omits whether existing tabs are affected, whether this creates a focused/active tab, and any slot-state assumptions.

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 tight sentences with the action and return value front-loaded and the multi-agent guidance second. No filler or redundancy.

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 simple creation tool with full schema coverage and no output schema, the description covers the essentials: what it does, its return, and the shared-slot isolation concern. Minor gaps remain around tab focus/activation semantics and interaction with other tab tools.

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 all four parameters (url, slot, agent, summary) are already documented with format hints. The description only references the slot indirectly and adds no syntax or constraint detail beyond the schema, so the baseline 3 is appropriate.

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 names a specific verb+resource ("Opens a new tab") and states the return value (tab ID), which cleanly separates it from siblings like browser_tab_select or browser_launch. It does not explicitly name an alternative, but the action is unambiguous.

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?

It gives a concrete when-to-use condition: "When agents share a slot, open your own tab and work only by its ID to avoid mixing." That is real usage context, though it stops short of naming sibling tools (browser_tabs, browser_tab_select) or stating when not to open a new tab.

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