new_page

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

Annotations only provide readOnlyHint=false. Description adds the return behavior ('Returns tab index'), which is behavioral information beyond what annotations provide. However, no details on error handling, loading state, or tab limits.

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?

Two sentences, each carrying essential information. No filler, front-loaded with the core action. Perfectly concise.

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 tool with full schema coverage and no output schema, the description adequately covers the return value. The tool's role among siblings is clear from context. No gaps remain.

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 already describes the 'url' parameter as 'Target URL' with 100% coverage. The description does not add additional meaning (e.g., accepted formats, protocols, validation rules). Baseline 3 is appropriate.

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?

Description clearly states 'Open new tab at URL' with a specific verb and resource. It unambiguously represents the tool's action and distinguishes it from siblings like navigate_page (navigate current tab) and select_page (switch to existing tab).

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?

Description implies usage is for creating a new tab given a URL, but no explicit guidance on when to use versus alternatives (e.g., when to open a new tab vs navigate existing tab). No exclusions or contextual conditions provided.

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