list_regions

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so safety is covered. The description adds real behavioral context beyond that: `auto` is always a valid region, and there is a maximum number of regions a single monitor may use — useful constraints an agent cannot infer from structured 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?

Two compact sentences with no filler; the primary purpose and the key output facts are front-loaded, and the usage hint follows economically.

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 read-only enumeration tool with full annotations and no output schema, the description adequately conveys both what is returned (regions, the always-present `auto`, the per-monitor cap) and how to use it. Only the precise return shape is left implicit, a minor gap given the annotations cover the rest.

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% with both optional params (project, workspace) fully documented, including their source (list_workspaces) and omit-for-default behavior. The description says nothing about these params, so baseline 3 applies since the schema does the heavy lifting.

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 the regions checks can run from) and enriches it with the exact content returned: the available regions plus the per-monitor cap. The mention of `auto` being always present further pins down the result set, so an agent can distinguish this config-lookup from sibling list tools like list_monitors or list_channels.

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 closing sentence 'Set a monitor's `regions` to use them' gives clear intended context, implying this should be called before create_monitor/update_monitor. It does not name those siblings explicitly or state any when-not condition, so it stops short of full routing guidance.

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