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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds that results include service lines (a return-content hint, valuable since there is no output schema) and the endpoint path, but says nothing about pagination behavior, rate limits, or result ordering.

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 short sentences with zero waste; the resource and return scope are front-loaded, and the endpoint is a compact secondary detail. Nothing is repeated from the schema or annotations.

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 all parameters documented, readOnlyHint covering safety, and no output schema to explain, the description is nearly sufficient. The note that service lines are included covers the main return-value expectation, though pagination flow is left entirely to the schema.

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 all five parameters (query, cursor, page_size, client_ids, status_ids) documented inline, so the baseline is 3. The description contributes no additional parameter meaning such as filter combination semantics or match behavior.

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 pairs a specific verb ('List') with a precise resource ('billing contracts with their service lines') and names the underlying endpoint. This distinguishes it cleanly from siblings like gorelo_list_invoices or gorelo_list_clients, though it does not explicitly contrast with those alternatives in text.

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?

There is no when-to-use, when-not-to-use, or alternative-routing guidance. An agent must infer from the name and siblings that this lists contracts rather than invoices or tickets, with nothing in the description to confirm that inference.

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