close_tabs

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

With no annotations present, the description carries the full behavioral burden and does so thoroughly: it warns that identifiers must belong to the same browser, that lifecycle generations are checked before removal, and that the ownership bypass flag is reserved for explicit operator requests. These are non-obvious behaviors that substantially affect call success and safety.

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?

Three dense sentences cover purpose, multi-tab constraints, ownership rules, and the special flag condition with zero filler. The most important action and identifier forms are front-loaded, and each sentence contributes new, necessary information.

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?

Given the tool's moderate complexity (multiple parameter combinations, ownership nuance) and the presence of an output schema, the description covers all decision-relevant aspects: what identifiers are accepted, the same-browser constraint, the default ownership guard, and the escape hatch for operator-requested closures. Nothing an agent needs to know before calling 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 0%, so the description must explain parameters on its own. It clarifies that tab_id can be a single identifier or a list, that session_id is an alternative composite identifier, that owner_id is required by default, and that only_if_agent_owned controls whether user tabs may be closed. This adds meaning far beyond the raw schema types.

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 opens with a specific verb and resource: 'Close one or more tabs by native tab id or composite session_id.' It precisely defines what the tool acts on and the two accepted identifier forms, making its purpose unmistakable even before reading the schema.

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?

It explicitly explains the default ownership restriction ('closes only tabs created by this MCP task'), the requirement for owner_id, and the exact condition for using only_if_agent_owned=false ('only for an explicit operator request'). This tells the agent when it is safe to use the tool and when not to, without needing to infer policy.

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