close_tab

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

No annotations are provided, so the description carries the full burden. It does disclose a meaningful behavioral trait the schema cannot: that this drives the user's actual Chrome browser via an extension, implying real, externally visible side effects. It omits, though, whether closing is reversible, what happens to page state, or what occurs with an invalid tab id.

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 short clauses, front-loaded with the environmental context and then the action. Every element earns its place, though the bracketed environment note is likely repeated boilerplate across sibling tools rather than specific to this action.

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, no-output-schema tool the description is adequate, but given zero annotation coverage a mutation-style action like closing a tab should say more about permanence and side effects than it does.

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 both parameters (intent, tab_id) are already documented structurally. The description only echoes 'tab id' without adding format, range, or sourcing detail, so the baseline 3 applies.

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?

States a specific verb+resource ('Close tab') and identifies the key selector ('by tab id'), which an agent can trivially distinguish from siblings like open_tab and switch_tab. It stops short of differentiating itself explicitly, but the intent is unambiguous.

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 bracketed prefix gives a real when-to-use constraint ('use only when the task requires acting on a real website'), which is genuine scoping guidance. However, it says nothing about when to close versus switch away, nor any prerequisites such as the tab existing or being non-active.

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