list_instances

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only says 'list' and does not state whether the operation is read-only, whether pagination applies, what fields are returned, or whether any permissions are required. The word 'list' implies retrieval, but little else is disclosed.

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?

A single sentence containing the relevant resource and scope, with no filler or repetition. It is appropriately sized for a one-parameter list operation.

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 simple list tool with one optional parameter, the description is nearly sufficient, but with no output schema or annotations it omits return shape, pagination, and authorization expectations. An agent can invoke it, but may not know what the result contains without additional information.

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 description coverage is 100%: folder_id already has a clear description with default-from-env behavior. The main description repeats the folder scope but adds no new parameter-level details, so the baseline 3 applies.

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?

The description names a specific resource (virtual machines/Compute) and scope (a Yandex Cloud folder), and the verb 'list' distinguishes it from single-instance or action-oriented siblings. It does not explicitly name alternatives, but the operation and resource are unambiguous.

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 scope 'in a folder' implies the tool is for enumerating VMs rather than fetching one or acting on one, but there is no explicit when/when-not guidance or mention of alternatives like get_instance, start_instance, or stop_instance. Usage must be inferred from sibling names.

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