close_tab

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

Annotations already indicate destructive behavior (destructiveHint=true) and non-read-only status, so the description does not need to restate that closing destroys a tab. It adds meaningful behavioral context beyond annotations by explaining the active-tab fallback when tabId is omitted.

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 front-loads the core purpose and immediately states the key optional-parameter behavior. There is no filler or repetition of structured annotation fields.

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 one-optional-parameter destructive action, the description covers what the tool does and the critical edge case (no tabId). Annotations cover the destructive and non-read-only nature, and no output schema is expected for this simple close operation. Nothing an agent needs to call it correctly is missing.

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%, and the tabId parameter is adequately described as 'The ID of the tab to close' in the schema. The tool description adds only the fallback behavior tied to omitting tabId, not new parameter-level semantics, so the baseline score of 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?

The description uses a specific verb and resource: 'Close a specific browser tab.' It clearly distinguishes this tool from siblings like open_tab, reload_tab, and focus_tab by naming the action it performs. The default behavior for absent tabId is also stated plainly.

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 invocation context: use a tabId to target a specific tab, or omit it to close the active tab. It does not explicitly enumerate alternatives or when-not-to-use scenarios, but the verb and sibling set make the intended use obvious.

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