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

Annotations already declare non-read-only, non-idempotent, non-destructive behavior, and the description adds nothing beyond that. It does not say whether this is a partial patch or full replacement, whether omitted fields are cleared, or whether code changes affect existing orders — all important for a mutation with a non-idempotent annotation.

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 single sentence is front-loaded and has zero waste, but it is under-specified rather than concise — nothing about update semantics or required inputs is conveyed. Efficient structure, insufficient content.

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 7-parameter mutation with an output schema and only partial annotation coverage, the description omits patch-vs-replace semantics, what happens to unspecified fields, and how ticket_type_ids scope the coupon. The schema and annotations cover safety hints, but the description leaves too much for the agent to infer before calling.

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 only 57%, and three parameters (is_enabled, coupon_code_id, ticket_type_ids) have no schema-level explanation at all. The description lists no parameters and does not compensate for the gap, so semantics like what ticket_type_ids restricts are left entirely undocumented.

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 and resource ('Update one coupon code') and scopes it to an event, so the agent knows exactly what entity is mutated. It does not distinguish this from the sibling tools create_coupon_code and delete_coupon_code, leaving sibling differentiation to the name alone.

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 use this versus create_coupon_code or delete_coupon_code, no prerequisites (e.g. needing event_id and coupon_code_id from a read/search call), and no exclusions. The only guidance is the implicit contrast between 'update' and the sibling verbs.

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