List available datacenters

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds behavioral context: it explains the pinger_url field facilitates latency measurement and that results include a 'code' to be used as datacenter_code, which is beyond the schema and aids correct usage. It doesn't describe pagination or return format, but for a list tool this is acceptable given read-only nature.

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 is efficiently structured: the first sentence states the primary purpose, and the second paragraph explains the practical usage with pinger_url and code selection. Every sentence adds value—no fluff or repetition. The key information is front-loaded, making it easy for an agent to quickly grasp the tool's function.

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 list operation with a single parameter, the description is complete. It explains the purpose, provides the practical workflow (ping, compare, pick code), and mentions the key fields returned (pinger_url, code). The parameter is fully documented in the schema, and the absence of an output schema is mitigated by the description highlighting relevant fields. Nothing essential is missing.

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?

The input schema already describes order_id as 'Agency Plan order ID' with 100% coverage, so the schema carries the parameter meaning. The description mentions 'given Agency Plan hosting order' which reinforces this but doesn't add new syntax or format details beyond the schema. Thus a baseline 3 is appropriate.

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 clearly states a specific action ('Lists') and resource ('datacenters available for provisioning a new website') scoped to a given Agency Plan hosting order. It distinguishes itself from VPS_getDataCenterListV1 by explicitly tying to Agency Plan hosting, and explains the 'pinger_url' and 'code' fields, making its purpose unmistakable.

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?

It clearly indicates when to use it (before creating a website setup on an Agency Plan order) and how to use the results (ping pinger_url, compare latency, pick nearest, use code as datacenter_code). It doesn't explicitly state when not to use it or name alternatives, but the scoping to Agency Plan hosting and the reference to website setup provide clear contextual guidance.

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