close_tab

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

With no annotations, the description bears the full burden and discloses important behavioral traits: CDP does not change focus, while IPC fallback will briefly change focus. This is beyond the obvious 'close' action and helps the agent anticipate side effects.

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 concise clauses within one sentence, front-loaded with the action and resource. Every word contributes information without 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 tool with no output schema or annotations, the description covers the core action, both invocation mechanisms, and the key behavioral difference (focus change). It is sufficiently complete for an agent to use effectively.

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 schema already provides descriptions for both parameters, but the tool description adds the crucial distinction that 'tab' uses CDP (no focus change) and 'index' uses IPC (focus change). This enriches the semantic meaning beyond the raw 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 the tool closes a tab, with the specific mechanism of matching by URL/title via CDP and an IPC index-based fallback. It is distinct from siblings like focus_tab or open_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?

The description implies when to use each mode (CDP for non-focus-changing close, IPC fallback when index is needed) and notes the side effect of focus change. It does not explicitly contrast with alternatives like focus_tab, but the context is clear enough.

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