firefox_list_tabs

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the lower bar applies. The description does add real behavior beyond them: the result set is restricted to tabs with persistent read access and others are silently omitted. It does not explain how that access is obtained or whether the filtering is per-tab or per-session.

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, front-loaded sentences with no padding; the core action comes first and the filtering caveat follows. The only cost is that the terse phrasing leaves "persistent read access" undefined rather than using that space to clarify it.

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?

With no output schema, the description should carry the shape of the return value, and it does not say what a listed tab contains or how access scope is represented. For a zero-parameter list tool this is adequate but not complete, since the agent cannot predict the response contents.

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?

The tool takes zero parameters, so the baseline is 4. There is nothing for the description to disambiguate in the input schema, and it correctly says nothing extraneous about arguments.

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") and adds a scope qualifier ("with persistent read access"). The second sentence clarifies that the result set is filtered rather than exhaustive, which helps distinguish it from tab-manipulation siblings like firefox_tab_action or firefox_tab_group, though the phrase "persistent read access" is not defined.

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?

Usage is only implied: an agent can infer this is the enumeration call, and "Other tabs are hidden" hints that firefox_request_access may be needed for the rest. But no alternative or condition is named explicitly, and the description never tells the agent what to do when a needed tab is missing from the list.

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