list_compute_instances

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the description does not need to restate safety. It adds useful context about environment selection and default behavior, but it does not disclose pagination, ordering, or response shape beyond the listed location and status fields.

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?

The description opens with a one-sentence summary and then provides a compact Args block. There is no filler, and every sentence either clarifies scope or parameter behavior.

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 read-only list tool with two optional parameters and strong annotations, the description is nearly complete. It covers the resource, key output attributes, and environment handling, though it stops short of fully specifying the return shape or pagination behavior.

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 0%, and the description fully compensates by documenting both parameters: limit as the maximum number of instances, and environment with concrete examples ('staging', 'production') and default behavior. This goes beyond the bare schema types and defaults.

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 states a specific verb and resource: 'List Compute Engine VM instances', and adds output scope with 'location and status'. This distinguishes it clearly from sibling list tools such as list_gke_clusters and list_sql_instances.

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 description implies when to use the tool by naming Compute Engine VM instances, but it does not explicitly route around alternatives or state when not to use it. There is no mention of sibling tools like list_gke_clusters, so an agent must infer the boundary from the resource name alone.

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