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

The annotations declare readOnlyHint=true, covering the safety profile. The description adds that the tool supports filtering, sorting, and expansion, and provides the REST endpoint. It does not disclose return format or pagination behavior, but the schema already covers page/limit parameters. This is adequate but not rich.

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 two sentences: the first states the action and key capabilities, the second provides the API endpoint. It is front-loaded, concise, and every sentence adds value with no redundancy.

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 list tool with good annotations and detailed schema, the description is sufficient. It clearly states the resource and the main features (filtering, sorting, expansion). While there is no output schema and no explicit return description, 'List invoices' implies a list of invoice objects, and the endpoint reference adds context. It could mention return format, but overall it is fairly complete.

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 each parameter having a description and examples. The description mentions filtering, sorting, and expansion, which maps to where/sort/expand but adds no syntax details beyond the schema. Thus it meets the baseline 3 but does not exceed it.

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 the tool lists invoices, with a specific resource (invoices) and a scope hint (typically subscription invoices). It also references the REST API endpoint. It does not explicitly name sibling tools, but the resource is unambiguous, so it partially distinguishes itself.

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?

No explicit guidance on when to use this tool vs alternatives. It says 'typically subscription invoices' but does not mention when to use this over swell_query or other list tools. There are no exclusions or alternative tool names, leaving the agent to infer usage from the resource name.

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