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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered; the description adds that results come newest-first, what field set is returned by default, and the caveat that omitting `select` returns hundreds of columns. It does not discuss page size/next_skip behavior, but the schema documents that.

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?

One dense sentence with the core behavior front-loaded, filters in the middle, and the alternative-tool routing at the end. No filler or repetition of schema mechanics.

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 no output schema, the description does its job by listing the returned fields and the default-column caveat. Pagination (next_skip/top/skip) is left entirely to the schema, which is acceptable but the one remaining gap for a paged list tool.

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 coverage is 100%, so baseline is 3, but the description adds interpretive meaning: what counts as unpaid (BalanceRemaining > 0), that customer_id is a Customer RecordID, that created_since needs a timezone-bearing ISO timestamp, and that `select` overrides the default field set. This is real value beyond the schema text.

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 and resource (list invoices) along with ordering (newest first) and the optional filters it supports, and explicitly distinguishes itself from method_query_records for aggregates. An agent can tell exactly what this tool returns without opening the schema.

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?

Gives concrete conditions for each filter (unpaid = BalanceRemaining > 0, customer_id = Customer RecordID, created_since = ISO time) and names the alternative tool (method_query_records with `apply`) for totals. Routing guidance is explicit rather than implied.

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