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

With readOnlyHint=true already covering safety, the description adds rate limits (60/min, 1000/day), page size (100 per page), request cost per call, and returned fields including optional rows. This is useful context beyond annotations, though auth and error behavior are not covered.

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?

Three compact sentences front-load the resource and returned fields, then filtering, then rate limits. No filler; every clause adds operational value.

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 10-parameter list tool with no output schema, the description covers return fields, filtering, paging, and rate limits. It omits details like default sort order or the full pagination response shape, but these are minor given the schema and endpoint context.

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 all 10 parameters are already documented in the schema. The description restates filter categories and optional rows but adds little syntax or semantic detail beyond what the schema provides.

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 ('List') and resource ('sales (client) invoices'), and lists the returned fields. It clearly separates sales invoices from other resources, though it does not explicitly name the purchase-invoice sibling to distinguish the two.

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?

Provides filter dimensions (date, client, number, payment status) and paging, but no explicit when-to-use or when-not-to-use guidance versus alternatives. Usage is implied by the filter options rather than stated as routing guidance.

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