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

The readOnlyHint annotation already declares this a safe read, so the safety profile is covered. The description adds that the response includes usage count, a modest value-add, but says nothing about not-found behavior or auth/permission requirements.

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?

Two tight sentences, front-loaded with the action and the lookup key; the trailing endpoint reference is compact and informative. No redundant or filler 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 read-only single-resource fetch with annotations covering safety and a fully documented schema, the description supplies enough for correct invocation. It could mention not-found handling, but nothing essential is missing.

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%, so the schema already documents event_slug, account_slug, and discount_code_id with examples. The description only echoes that the id is numeric, adding no new meaning, 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?

State a specific verb (fetch), resource (a single discount code), and lookup key (numeric id), plus an extra detail about the returned usage count. This clearly separates it from the sibling tito_list_discount_codes, which is plural and unfiltered.

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?

Phrasing 'Fetch a single discount code by its numeric id' implies this is the lookup-by-id path versus the list sibling, but no when-to-use, prerequisites, or named alternative is stated. Usage is left to inference.

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