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

The readOnlyHint=true annotation already establishes the safe-read profile, so the bar is lower. The description adds that results can be scoped by contact/project/status, which is useful context, but says nothing about pagination behavior, default result size, or the shape of returned data.

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, front-loaded with the action and scope, followed by the underlying endpoint reference. Nothing is wasted and the key information comes first.

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 8 optional parameters and no output schema, the description is adequate but thin: it does not describe the paginated return structure or default page size, which an agent would need since no output schema exists. For a filtered-list tool it is minimally sufficient.

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% across all 8 parameters, so the schema fully documents page, sort, view, contact, project, per_page, updated_since, and nested_invoice_items. The description adds no syntax or format detail beyond what the schema already provides, so the baseline of 3 is correct.

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 states a specific verb+resource ('List sales invoices') and adds scope qualifiers ('optionally for one contact or project, filtered by status'). This distinguishes it from get_invoice and create_draft_invoice, but it never explicitly names those siblings or clarifies what a list returns vs. a single get.

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?

Usage is only implied: the mention of filtering by contact, project, or status hints at when the tool is useful, but there are no explicit when-to-use/when-not statements or named alternatives (e.g., get_invoice for a single invoice).

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