Reopen a closed tab

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

Annotations only declare readOnlyHint=false, so the description must carry the behavioral load, and it does: 'closed in this session' is the key constraint — the tab is only recoverable from SessionStore, not after a restart. It also discloses the undo relationship to browser_close_tab, making the pair's reversibility explicit. It does not say how an invalid index is handled, which keeps it from a 5.

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 sentences, zero filler, front-loaded with the action and immediately followed by the index semantics and the sibling routing hint. Every clause is load-bearing.

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 single-optional-parameter tool with no output schema, this covers scope (session only), parameter semantics, and the inverse relationship. The only gap is error behavior for an out-of-range index, which is a minor omission rather than a blocker.

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 coverage is 100%, but the schema description only says '0-based position among closed tabs (default 0)' and omits the ordering direction; the description supplies that critical detail — 'index 0 is the most recently closed tab' — and points to browser_list_closed_tabs as the source of valid values. That is genuine added meaning beyond the 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?

States a specific verb and resource (reopen a closed tab) plus the underlying mechanism (SessionStore.undoCloseTab). It also names the two siblings it relates to, browser_close_tab (the inverse) and browser_list_closed_tabs (the index source), so an agent can distinguish it from the ~130 other tab tools without opening any 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?

Explicitly tells the agent where to get valid indices (browser_list_closed_tabs) and frames the tool as the inverse of browser_close_tab, which gives a clear use condition. It stops short of stating failure modes, e.g. what happens with a stale or out-of-range index, but the positive guidance is strong.

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