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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond them by disclosing the shape of the result (capabilities, package inclusion, companion dependencies expressed with a concrete 'Accounting works from Invoicing & Payments or the Customer Portal' example).

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 sentences, front-loaded with the resource and scope, then the argument source. The parenthetical example is short and concretely illustrates the 'needs alongside it' concept rather than padding.

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?

With no output schema and a single enum parameter, the description carries the remaining burden, and it does so by describing what fields the response conceptually covers. It stops short of detailing the response structure or error behavior, but nothing required to invoke it correctly 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?

Schema coverage is 100% and the enum already enumerates every valid id, so the baseline is 3. The description adds provenance guidance — take the id from ubm_list_services rather than inventing one — which is meaning the schema cannot supply.

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 ('One UBM service in detail') and enumerates exactly what the detail contains: behavior, packages that include it, and prerequisites. The pairing with 'Pass the service id from ubm_list_services' makes clear this is the single-service lookup versus the sibling that lists all services.

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 tells the agent where the required argument comes from ('the service id from ubm_list_services'), which implies the natural call order. It does not name a when-not case or an alternative detail tool, but no such alternative exists among the siblings.

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