browser.close_tab

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

The description discloses the important behavioral constraint that the tool only closes a tab if more than one tab is open, preventing closure of the last tab. This adds value beyond the annotations, which already indicate destructive behavior (destructiveHint=true).

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 a single, concise sentence that conveys the core functionality without unnecessary words. It is front-loaded and efficient, earning its place with no fluff.

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?

The description covers the basic action and precondition but lacks details on error handling (e.g., what if the index is out of range) and return behavior. For a destructive tool with no output schema, more context would be beneficial, but it is minimally adequate.

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?

With 0% schema coverage, the description should compensate but only mentions 'tab index' to clarify the 'index' parameter. It does not explain 'session_id' or provide details on parameter ranges or formats, leaving significant ambiguity.

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 the action: closing a tab by index. It is specific, using verb 'close' and resource 'tab index', and distinguishes from siblings like 'close_session' which closes all tabs. However, it does not explicitly mention the browser session context, which is clear from the parameter 'session_id'.

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 implies a precondition (more than one tab open) but provides no guidance on when to use this tool versus alternatives like 'close_session' or 'activate_tab'. There is no explicit when-to-use or when-not-to-use advice.

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