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

Annotations already indicate a non-read-only, idempotent, non-destructive operation. The description adds meaningful behavioral constraints beyond annotations: only open tickets can be updated, and descriptions must follow strict HTML tag restrictions. It does not disclose failure behavior for closed tickets or return values, but the constraints provided are valuable.

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 description is heavily duplicated: the initial paragraph repeats the same content as the Markdown '# update_ticket' section, including the HTML rules and 'Only open tickets can be updated' nearly verbatim. The parameter section also repeats schema details. While structured, the redundancy makes it longer than necessary and reduces readability.

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?

The description covers prerequisites (fetch_open_tickets), constraints (only open tickets), and parameter validation details. However, it omits return value/error handling behavior, and the duplication detracts from completeness. For a fairly simple update tool with adequate schema and annotations, the content is sufficient but not fully polished.

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 all three parameters are already documented in the schema. The description largely repeats the same parameter details (e.g., 'New ticket subject (max 200 characters)') and adds no new semantic meaning beyond what the schema provides. The only slight addition is the instruction to obtain case_id from fetch_open_tickets, which is already implied by the parameter description.

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 clearly states 'Update an open support ticket' with a specific verb and resource, and explicitly limits scope to open tickets. It distinguishes the tool from siblings like create_ticket, delete_ticket, and resolve_ticket by instructing users to fetch_open_tickets first and noting that only open tickets can be updated.

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?

The description provides clear guidance on when to use the tool: 'Use fetch_open_tickets first to get the case_id' and 'Only open tickets can be updated.' It implies when not to use it (for closed tickets) but does not explicitly name alternatives such as resolve_ticket for closing tickets, so it stops short of full exclusion coverage.

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