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

readOnlyHint=true already tells the agent this is a safe read. The description's only added context is the REST endpoint mapping, which is minor for an agent; it says nothing about error behavior for missing/inaccessible ids or what ticket data is returned.

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 short, front-loaded sentences with no filler; the purpose leads and the endpoint reference trails as optional detail. Nothing in the text is 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 single-parameter read tool with annotations covering safety and a fully documented schema, this is nearly sufficient. With no output schema, a brief note on what the ticket payload contains would have closed the 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% with a single integer parameter already documented as 'Numeric ticket id (required)'. The description merely restates 'by id' and adds no format, range, or lookup-strategy detail beyond the schema, so baseline 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?

States a specific verb and resource ('Fetch a single ticket by id') and even names the underlying REST path, so the agent knows exactly what it retrieves. It does not explicitly differentiate itself from siblings such as zendesk_list_tickets or zendesk_get_ticket_metrics, which keeps it off a 5.

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 when-to-use or when-not-to-use guidance. It never says whether to prefer this over zendesk_search or zendesk_list_tickets when the id is unknown, nor what prerequisites (auth, ticket visibility) apply. The 'by id' phrasing only weakly implies the condition.

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