listTabs

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 adds value by specifying the returned data (URLs, titles, active status) and the tab index for use with switchTab. It also disambiguates that programmatically opened tabs are included, which is useful context beyond the tool name.

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 concise sentences, front-loaded with the main action and followed by relevant usage context and a note on the return value. Every sentence earns its place with no 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 simple read-only listing tool with no parameters and no output schema, the description is complete. It states what is listed, the data fields included, and how the result relates to another tool (switchTab). No critical information is missing for the agent to select and invoke this tool correctly.

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 tool has zero parameters, so schema coverage is trivially 100%. The description adds no parameter-specific information, but none is needed. The baseline of 4 is appropriate for a no-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 the tool's function: 'List all open browser tabs with their URLs, titles, and active status.' It uses a specific verb ('list') and resource ('browser tabs'), and it distinguishes itself by noting it includes tabs opened via window.open/target='_blank', which sets it apart from any sibling that might only handle manually opened tabs.

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 clear context for when to use the tool: 'Use this to see all tabs opened manually or via window.open/target='_blank'.' It gives an explicit intended use case, but it does not mention alternative tools (like switchTab) or exclude scenarios, so it stops 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.