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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the code formats (two-letter probe codes, region names) and the underlying endpoint paths, but says nothing about the return shape or error behavior on an invalid code.

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 the core resource front-loaded; the region examples are dense and useful. The opening is a fragment, but no sentence is wasted.

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 reference lookup with no output schema, the description is adequate: it identifies the data, the valid value formats, and the endpoints. Only the return shape/error semantics are left implicit, which is a minor gap for this tool type.

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 100%, so the baseline is 3, but the description earns extra by supplying concrete region values (nam, lam, eur, eao, wlw) and the two-letter code format that the schema does not enumerate. This materially helps the agent pick valid values.

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 the specific resource (probe servers and regions) and clarifies it is the reference data that a check's run locations use. Combined with the name/title, an agent can tell what it retrieves, though it never states the verb 'retrieve/list' explicitly. It is clearly distinct from the check/contact/schedule siblings.

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 phrase 'the values a check's run locations use' implies the context (resolving codes for check configuration), but there is no explicit when-to-use, when-not-to-use, or named alternative. Usage is inferable but not stated.

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