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

Annotations already declare readOnlyHint=false, openWorldHint=true, and destructiveHint=false. The description adds genuinely useful context beyond that: Bandcamp sends the buyer an email (an external, irreversible side effect), only one order can be handled per call, per-call confirmation is on by default, and a Cotlet API key with app access is required.

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 email-with-tracking-number-notice point is stated twice ('Bandcamp emails the buyer with the tracking number and note' and 'Bandcamp then emails the buyer with the tracking number and note you pass'), and 'one order per call / marks one order shipped' is also duplicated. The content is useful but noticeably redundant.

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 mutating, externally-visible operation, the definition covers the important ground: the email side effect, one-order scope, confirmation default, and the API-key prerequisite. No output schema exists, but the effect is described, so little is missing for correct invocation.

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 100%, with order_id, note, and tracking_number each documented in the schema. The description restates that tracking number and note are passed into the buyer email but adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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+resource ('Mark a merch order shipped') and the key side effect (emails the buyer with tracking number and note). It is clearly distinguishable from read-only siblings like list_merch_orders and from bandcamp_refund_merch_order, though it does not name those alternatives 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 context is implied rather than stated: 'One order per call' and the confirmation requirement describe how to invoke it, and the schema points to list_merch_orders for the order_id. However, there is no explicit when-to-use vs. when-not, and the alternative for bulk shipping is not addressed.

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