Get fields for service

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the prerequisite relationship to CreateSubscription / ValidateFields, but does not describe return shape, failure behavior, or any other operational detail.

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 a single compact sentence that front-loads the purpose and use context. It has a minor redundancy in repeating the tool name as a prefix, but otherwise contains no bloat.

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 low-complexity, read-only retrieval tool with fully described parameters, the description gives enough context to invoke it correctly before create/validate flows. It does not explain the returned field-definition structure, and there is no output schema, but the broad return content is implied by the tool purpose.

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%, so productName, parentAccountId, and secondaryParentId are already documented in the schema. The description adds no parameter-level meaning beyond that, making the baseline 3 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?

States a specific verb and resource: field definitions for a service. It also ties the result to CreateSubscription / ValidateFields, which helps distinguish it from generic service-listing tools, though it does not explicitly distinguish it from sibling field-getters for upgrade/renew.

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?

Explicitly says the tool is needed before CreateSubscription / ValidateFields, giving clear usage context. It does not name exclusions or alternatives such as get_subscription_fields_for_upgrade or get_subscription_fields_for_renew, so it falls short of a 5.

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