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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true), it discloses several non-obvious traits: exactly one refund per transaction, the reason is surfaced on the booking, notify=false suppresses customer notification, a per-call confirmation policy, and the required Cotlet API key. These are substantial behavioral details an agent needs before invoking.

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?

Purpose is front-loaded, which is good, but the text carries repeated boilerplate and redundancy: 'One refund per charge' is restated later as 'one refund per transaction, so a second refund fails,' and the confirmation policy is stated twice ('By default you confirm each call...' and 'confirm with the user before each call'). Trimming would help.

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 mutation tool with no output schema, the description covers constraints, side effects (notification, reason display), and auth, which is strong. It stops short of describing what a successful call returns (refund confirmation/amount), the one remaining gap.

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 the schema already documents all four parameters (amount includes tax/omit for full, notify default true, reason shown, charge_id source). The description reinforces these but adds little syntax or meaning beyond the schema, so the baseline 3 is appropriate.

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 (refund) and resource (a charge), and further scopes it as full-or-partial, which is more precise than the title. An agent can immediately tell this is the money-moving refund operation and not a listing/lookup tool like bookingkoala_list_charges.

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 clear context for use (refund a charge, fully or partially via amount) and a when-not condition (a second refund on the same charge fails). It does not name sibling alternatives explicitly, but for this operation there is no plausible competing tool, so guidance is effectively complete.

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