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

With no annotations supplied, the description carries the full burden and does meaningful work: it discloses ordering (newest first), the record contents (token spent/granted/plan-component change with before/after balances), and a non-obvious diagnostic property about rows missing for observed balance changes. It stops short of stating read-only status explicitly, auth requirements, or what happens when more than 500 rows exist.

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 and ordering constraint are front-loaded in the first sentence, and the anomaly note follows logically. The JSDoc-style @param/@return tags are slightly mechanical but justified given the 0% schema coverage and the existing output schema.

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 two-parameter read tool with an output schema, the description covers purpose, ordering, row contents, parameter bounds, and where the rows live in the response ("values"). The remaining gap is truncation behavior at the 500-row cap and whether older history is retrievable.

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 0%, so the description must compensate, and it does: customer_id is identified as the customer's database id, and limit is given a meaning, a 1-500 range, and a default of 50 that the bare schema lacks. This is a clear value-add over the schema, though customer_id's provenance (where to obtain it) is unstated.

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?

"Returns the customer's FUP token audit trail, newest first" gives a specific verb (returns), resource (FUP token audit trail) and ordering. It is clearly distinguishable from siblings like customer_get_credit_balance or customer_deduct_from_fup, though it never names an alternative explicitly.

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 note that an unmatched balance change signals a write from outside the paywall tools hints at reconciliation/diagnostic use. There is no explicit when-to-use or when-not-to-use statement, and no pointer to the sibling tools that also surface balance or transaction data.

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