Manage owned tabs

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

Annotations already declare readOnlyHint=false, openWorldHint=true, and destructiveHint=true, so the description doesn't need to restate those. It adds valuable behavioral context: popups stay open and appear in snapshots, switching is required to work in them, and closing the last tab closes the session. This goes beyond the annotations and helps the agent understand side effects.

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?

Three sentences, each carrying distinct information: the action scope, the popup behavior, and the session lifecycle. No filler or repetition of schema details. The most important usage constraint (popups) is front-loaded.

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 multi-action tool with no output schema, the description covers the key behavioral nuances: popup handling, session scoping, and session closure. It doesn't describe return values or error conditions, but the action enum and parameter names give a reasonable picture. The missing parameter-to-action mapping is a minor gap, but the description is otherwise complete enough for an agent to invoke it 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?

Schema description coverage is only 25% (only session_id has a description). The description does not explain the meaning of url, tab_id, or the action enum values beyond the enum itself. It implies that 'new' likely needs a url and 'switch'/'close' need a tab_id, but it doesn't explicitly map parameters to actions. Baseline 3 is appropriate because the description adds some context but doesn't fully compensate for the low schema coverage.

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 states a clear verb set ('List, open, switch or close tabs') and a specific resource ('tabs within a session'), and it distinguishes itself from sibling tools by noting that only this session's pages are accessible. It also clarifies the popup behavior, which is a unique trait not evident from the name or schema.

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 gives explicit context: popups stay open and appear in snapshots, and you must switch explicitly to work in them. It also states that only this session's pages are accessible, which implies when to use this tool versus other tab tools. However, it does not explicitly name alternative tools or say when not to use this tool, so it falls just 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.