list_compute_instances

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

No annotations are provided, so the description carries the burden. It clearly indicates a read-only list operation (based on 'List'), but doesn't add context about authentication, permissions, rate limits, or behavior on empty results. It discloses core behavior but is minimal.

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?

Compactly structured docstring: one-line summary, Args with two bullets, Returns line. No fluff, though the Returns line slightly repeats the summary. Efficient and well-organized.

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 no annotations and no output schema, the description covers the purpose, both parameters, and return type. It could mention that listing is across all zones unless zone is specified, but the optional zone implies that. Adequately complete.

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 has no descriptions (0% coverage), but the description provides clear semantics for both parameters: project_id and zone, including an example for zone. This fully compensates for the schema gap.

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?

Describes the tool as 'List Compute Engine instances in a GCP project' – a specific verb and resource. Distinguishes from siblings like list_gcp_projects and get_instance_details by targeting the instance listing specifically.

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?

Provides implied usage through its description (list instances when needed), and the optional zone parameter indicates filtering usage. However, it lacks explicit guidance on when to use this vs alternatives like get_instance_details or start_instance, and doesn't mention any exclusions.

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