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

With no annotations, the description carries the full burden and largely meets it: it explains that `as_of` reconstructs open amounts from posted journal lines rather than the cached amount, that items are included regardless of current status, that `status` is actively refused rather than silently ignored, and that `original_amount`/`status` on rows remain current facts. It stops short of stating the read-only/no-mutation guarantee explicitly, so not a 5.

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 purpose is front-loaded, but the body is padded with internal ticket references (ZCT-577 twice), a narrative about how the browser screen used to filter rows, and the throwaway "the screen says so." The core semantics are valuable; the provenance storytelling is not, and it dilutes an otherwise dense definition.

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 6-parameter list tool with no output schema and no annotations, the description covers the tricky filtering semantics and even names two row fields (original_amount, status), which partially compensates for the missing return schema. What remains unstated — pagination behavior and the row shape beyond those two fields — is minor but not fully covered.

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 0%, so the description must compensate, and it does so well for the non-obvious parameters: it defines `direction` as a server-side filter, explains exactly what `as_of` computes, and documents the `as_of`+`status` interaction. It says nothing about `limit`, `offset`, or `company_id`, but those are self-evident, leaving only a minor gap.

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 opening states the resource precisely (AR/AP subledger open items) and implies the list/pagination verb ("one page"), plus a permission qualifier ("member read"). It is clear what the tool returns, but it never distinguishes itself from siblings such as list_ar_invoices or list_gl_journal_entries, so it falls short of a 5.

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?

It gives concrete usage rules for two parameters (omit `direction` for both directions; `status` is refused with `as_of`), which is real when-to-use guidance. However, it offers no routing guidance relative to the many sibling list/ledger tools, so an agent still has to guess whether this or list_ar_invoices is the right call.

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