select_page

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

Discloses the key behavior of selecting the active tab and the precedence rule for index. The annotation readOnlyHint=false already signals mutation, and the description adds valuable context about how criteria resolve conflicts, going beyond what the annotation provides.

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?

A single sentence that clearly conveys the purpose and a key rule. No superfluous words, front-loaded with the action and selection criteria.

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 selection tool, the description covers the mechanism and the precedence rule. It does not mention return values or error cases, but given the absence of an output schema and the clarity of the function, this is sufficient for an agent to understand expected behavior.

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 covers all three parameters with concise descriptions (e.g., 'Tab index (0-based, most reliable)'), so the description adds little beyond the schema. The precedence rule is already implied by 'most reliable' in the schema, offering minimal additional semantic value.

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?

Clearly states the tool selects the active tab using three criteria (index, URL, or title). This distinguishes it from sibling tools like navigate_page or close_page, which have different actions.

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 clear context that selection is by index, URL, or title, and explicitly states index takes precedence when multiple criteria are given. It does not explicitly mention alternatives or when not to use, but the context is unambiguous and the precedence rule offers practical guidance.

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