open_tab

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

Beyond the annotations, the description reveals that the tab opens in the background by default to avoid disrupting the user, which is behavior not captured by readOnlyHint, openWorldHint, or destructiveHint. It also discloses the return value. This is useful behavioral context that annotations alone do not provide.

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?

The description is concise, front-loaded with the core action, and each sentence adds distinct value: what it does, the default behavior and rationale, and the return value. No filler or redundancy.

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 two-parameter action tool with full schema coverage and relevant annotations, the description is complete: it covers behavior, default semantics, return value, and user impact. No output schema is required since the return type is mentioned explicitly.

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 100%, so the parameters are fully documented in the schema. The description adds a brief user-context rationale for the background default, but largely reiterates what the schema already states, so it does not significantly elevate parameter understanding beyond schema.

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 clearly states a specific verb ('Open') and resource ('a new browser tab') with the specified URL, which distinguishes it from sibling tools like close_tab, list_tabs, and focus_tab. It also mentions returning the new tab ID, adding useful purpose specificity.

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 clear context on default behavior (background opening) and explains when the 'active' parameter should be set to true, helping the agent decide appropriate usage. It does not explicitly reference alternative sibling tools, but the context is sufficient for this simple operation.

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