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

Annotations already declare readOnly=true and destructive=false, so the safety profile is covered. The description adds genuine context beyond that: it states the return is broken into expiry-dated entries, that redemption requires at least 10 KlookCash, and that a Cotlet API key with access to this app is needed. The auth requirement and redemption rule are non-obvious and useful.

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 opening two sentences say the same thing twice ('entries it is made of, each with its expiry date' repeats 'expiry date of each part'), and comma-spliced clauses hurt readability. The tool's core promise is front-loaded, but the redundancy and awkward phrasing cost it.

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 carries the return-value burden and does so: it names the balance and its expiry-dated constituent entries. Combined with the stated auth requirement and the 10-unit redemption rule, an agent has enough to call and interpret this zero-parameter read correctly.

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?

Parameter count is zero, so the baseline is 4. The description reinforces this explicitly with 'It takes no parameters.', matching the empty schema and eliminating any ambiguity about input expectations.

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 second sentence gives a clear verb+resource: it returns the KlookCash balance plus the constituent entries, each with an expiry date. It is trivially distinguishable from every sibling (no other tool touches KlookCash). The first sentence, however, is garbled ('KlookCash on your account with the expiry date of each part'), which mutes the opening punch.

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?

There is no statement of when to call this versus alternatives, nor any precondition beyond the passing mention that it mirrors 'the Klookcash page in your profile'. The agent is left to infer the trigger condition entirely.

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