tab_close

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

With no annotations, the description carries the full burden, but it only mentions the core close action and selection semantics. It does not disclose what happens when the index or url_contains does not match a tab, whether the close is irreversible, or what effect closing the active tab has.

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?

A single, front-loaded sentence that communicates operation and both selection modes with no filler. It is compact and immediately parseable.

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 required fields and no output schema, the description is largely self-contained: it explains both selection modes and the active-tab default. It lacks edge-case behavior, but those are minor for a close operation.

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 description adds meaning to the otherwise undocumented index parameter by explaining that -1 targets the active tab, and it identifies url_contains as an alternative selector. The schema separately documents that url_contains overrides index, so the description covers the main semantic gap.

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 states the operation (close) and resource (a tab), and specifies the two selection modes: by index with -1 meaning active, or by url_contains. This is immediately distinguishable from tab_new, tab_select, and browser_close.

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?

There is no guidance about when to use this tool rather than alternatives such as browser_close, or any conditions or exclusions. The description only defines the close action; an agent is left to infer that this is the tool for tab-level closure.

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