tabs

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

With only an openWorldHint annotation, the description carries the behavioral burden and does so well: default-active-tab semantics for `select`/`close`, prior-tab reactivation after close, id non-reuse, automatic popup registration, and viewport-snapshot return on `new`. It doesn't describe what `select`/`close` return or any failure/error behavior, leaving a minor gap.

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?

Front-loaded with the tool name followed by per-action clauses, so an agent can scan for its action quickly. The nested parentheticals make it dense and slightly run-on, but every clause conveys a distinct behavior rather than restating the schema.

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 4-parameter, 4-action tool with no output schema and minimal annotations, the description supplies the activation, ordering, and id-lifecycle rules an agent needs. Missing only return-value detail for `select`/`close` and any failure modes such as closing an invalid or already-closed tab id.

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 only 25% (just `tab`), so the description must compensate, and it largely does: `background`, `url` (only meaningful for `new`), and the `action` enum values are all given operative meaning in prose. It does not state whether `url` accepts relative paths or must be absolute, nor that `tab` is invalid for `new`/`list`.

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?

Names the resource (tabs) and enumerates all four operations — list, new, select, close — with a concrete behavior for each, including the exact list output shape. It also distinguishes itself from the `snapshot` sibling by noting `new` returns only a viewport snapshot and directing full-page capture elsewhere.

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?

Explicitly routes to an alternative ("call snapshot for the whole page") and states conditions such as `background:true` suppressing activation and headed-mode-only fronting for `select`. It lacks guidance on when to open a new tab versus using `navigate` in the current tab, so it stops short of full when/when-not coverage.

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