List user contexts (containers)

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

readOnlyHint=true already establishes the safety profile, so the description only needs to add context. It usefully discloses the invariant that a "default" context always exists, which is real behavioral information, but says nothing about ordering, whether ids or names are returned, or whether the list can be empty.

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, zero waste, with the identity of the resource front-loaded and the existence invariant second. Nothing repeats the title verbatim beyond what is needed.

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 zero-parameter read-only list with no output schema, the description covers what the tool enumerates and the one non-obvious invariant (the default context). A brief note on return shape (ids vs. names) would close the remaining gap, but nothing an agent needs in order to call it 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?

The tool takes zero parameters, so the baseline is 4; there is nothing for the description to disambiguate. The description adds no spurious parameter-like guidance.

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 BiDi user contexts") and the parenthetical in the title plus the "containers" framing makes clear this is not tab/window enumeration. It is clearly distinct from browser_list_tabs and browser_list_windows, though the description itself never names those siblings to make the contrast explicit.

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 note that "the default one always exists; others are containers created via browser.createUserContext" implies when this list is useful and where entries come from, but there is no explicit when-to-use / when-not-to-use guidance. It also references a BiDi command name rather than the sibling tool browser_create_container, which an agent may not connect to the actual callable.

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