close_page

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

Annotations only declare readOnlyHint=false, so the agent already knows this is a mutation. The description adds a meaningful behavioral constraint: the last open page cannot be closed. It does not explain what happens to page state, whether closing discards unsaved data, or what errors occur for invalid page IDs.

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 sentences, front-loaded with the core action and followed by the key constraint. There is no unnecessary text.

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 one-parameter page-closing tool with full schema coverage and no output schema, the description provides enough context to invoke it correctly. The minor gap is that it does not clarify the 'index' versus 'ID' terminology or the effect on the active page, but those are secondary for this 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?

Schema description coverage is 100%, so the parameter is already documented as the page ID and the agent is told to call list_pages. The description adds little beyond restating the parameter, and it uses 'index' while the schema says 'ID', which is potentially ambiguous rather than clarifying.

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 a specific verb and resource: 'Closes the page.' It also clarifies that the page is identified by index, which helps an agent understand the operation. However, it does not explicitly distinguish this tool from siblings such as select_page, new_page, or browser_stop, so it falls short of a 5.

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 provides no guidance on when to use close_page versus alternatives. 'The last open page cannot be closed' is a constraint on the action, not a usage guideline or comparison to sibling tools.

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