Recently closed tabs

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

Goes well beyond the readOnlyHint annotation: it discloses the backing API (SessionStore.getClosedTabData), the return ordering, the ephemeral lifetime ('empty after a restart'), and that the returned index is the handle for reopen. These are exactly the traits an agent would otherwise have to guess.

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 short sentences, front-loaded with what the tool returns and its ordering, then lifetime constraint, then sibling relation. No filler and nothing repeated from annotations.

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 read-only, no-output-schema list tool this is nearly complete: ordering, lifetime, and the semantic meaning of the index are covered. It doesn't sketch the other fields per entry (title, URL, timestamp), which would fully close the gap given there is no output schema.

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% and the single 'limit' parameter is fully documented in the schema (default 10, max 50, exclusive minimum 0). The description adds nothing about it, so the schema does the work — the baseline 3 for a fully covered single-param tool.

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 ('List tabs that were closed in this session') plus the scope (session-only, in-memory) and ordering (newest first). It also names the sibling that consumes its output (browser_reopen_closed_tab) and the sibling it complements (browser_close_tab), so it is distinguishable from browser_list_tabs at a glance.

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 links the returned index to browser_reopen_closed_tab and labels itself the counterpart of browser_close_tab, which gives clear guidance on the follow-up action. It stops short of stating an explicit when-not-use condition or naming a competing alternative directly, but the usage path is unambiguous.

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