Select page

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

Beyond annotations (idempotentHint, etc.), the description discloses that selection is sticky, indices shift as tabs open/close, and if the selected tab is closed the selection is dropped and default applies. Also explains the bring_to_front parameter's effect on backgrounded page animations. No contradiction with annotations.

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 paragraphs, 76 words. The first sentence is direct and purposeful. The remaining sentences each add context on behavior and usage. Slightly verbose but every sentence earns its place.

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 stateful selection tool, the description covers purpose, default behavior, when to use, index semantics, side effects, and failure mode (tab closed). Output schema exists so return format needn't be described. Well-rounded and complete.

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 covers 100% of parameters with descriptions. The description adds context about indices shifting, but page_id semantics are already in the schema. Bring_to_front is fully described in the schema, so the description adds little beyond what structured data already provides.

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 clear verb+resource: 'Choose which open tab every subsequent tool call acts on.' It distinguishes from sibling tools like list_pages (which lists) and navigate_page (which navigates), and explains the default selection behavior.

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?

Provides explicit guidance: 'needed when a click opened a tab you now want to drive, or when working across several sites at once.' Also clarifies that without selection, tools act on the most recently opened tab, and that indices come from list_pages — giving a direct reference to the related tool.

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