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

Annotations only provide destructiveHint=true, so the description carries most of the burden. It usefully discloses that creation is effectively reversible via update (quantity/end_at) and gives the underlying API path, but omits auth/permission requirements, error behavior, and what happens on duplicate codes.

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?

Three front-loaded sentences with no filler; the type explanation comes before the undo hint and the raw API path. The 'Tito: POST /:account/:event/discount_codes' line is marginally useful for debugging but is the weakest sentence.

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 13-parameter mutation tool with no output schema, the description covers purpose, type semantics, and the undo path, but says nothing about what is returned (e.g. the created code/id) or the permission/scope needed, which an agent needs before committing a write.

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 meaning beyond the schema: it ties value units to the type ('value = percent' vs 'flat amount off per ticket, in the event currency'), and the currency qualifier is not present in 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+resource ('Create a discount code for an event') and immediately clarifies the domain-specific type enum semantics, which is the main ambiguity for a caller. It also names the sibling tool used to reverse the action, so an agent can distinguish this create from the update/delete paths.

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?

Explicitly routes the agent to tito_update_discount_code for undoing changes ('Undo by editing it (e.g. quantity or end_at)'), which is real when-to-use-this-vs-alternative guidance. It falls short of a 5 because it gives no prerequisites (auth/scope) or when-not-to-use conditions.

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