containers_list

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

With no annotations, the description carries the full burden and does reasonably well: it discloses that IDs are opaque, that default_cookie_store_id marks normal browsing, that names may repeat, and that IDs are profile-local and must never be reused elsewhere. It never explicitly states the operation is read-only or whether results are paginated, which keeps it below 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?

Front-loaded with the return shape, then the profile scoping rule. Minor redundancy between 'IDs belong to the connected profile' and 'All object IDs are local to that profile', but no sentence is wasted overall.

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-parameter list tool with an output schema and no annotations, it covers the required prerequisite, the profile-scoping constraint, the meaning of the default cookie store, and the non-uniqueness of names. An agent has everything needed to call it correctly and interpret the IDs.

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 0%, so the description must compensate, and it does: it declares profile_id required, tells the agent where to obtain it (profiles_list), and explains that all object IDs are scoped to that profile. It omits the type (integer), but the semantic scope is well covered.

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+resource ('List Firefox containers') and even the shape of the result (cookie_store_id, name, color, icon, default_cookie_store_id). It is unmistakably the read-only listing counterpart to containers_create/update/remove, though it never names a sibling explicitly.

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 supplies a prerequisite ('profile_id is required: obtain it from profiles_list'), which tells the agent how to call it, but not when to choose it over alternatives such as containers_update or tabs_list. Usage is only implied by the 'list containers' framing.

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