browser_list_tabs

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the output fields (tabId, label, URL, title, active tab) and the verb 'List' implies a non-mutating operation. This is sufficient for a read-only listing tool, though it does not explicitly declare 'read-only' or discuss error conditions.

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 two sentences with no superfluous words. The first sentence states the core function, and the second sentence provides output details and usage context. Every word earns its place, making it highly concise and well-structured.

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?

This is a simple tool with no parameters and no output schema. The description covers purpose, output fields, and usage context, which is complete for an agent to decide when and how to use it. The lack of an output schema is mitigated by listing the returned fields directly in the description.

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 has zero parameters, so the baseline per the rubric is 4. The description does not need to explain parameters, and the schema coverage is effectively 100% since there are no parameters. No additional semantic information is required.

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 opens with a specific verb and resource: 'List all browser tabs bound to this agent.' This clearly states what the tool does and inherently distinguishes it from sibling tools, which are all actions (close, navigate, click, etc.) rather than listing operations. The mention of returned fields reinforces the purpose.

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: 'Use this to discover what's available before issuing tool calls that need a specific tab.' This tells the agent when to invoke the tool, which is a clear context. However, it does not explicitly mention alternatives or when-not-to-use scenarios, so it falls short of a 5.

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