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

Discloses effects far beyond the annotations: status becomes waiting_staff, a system message is emitted, an audit event `support_case_reopened` is recorded, and `ops.support.customer_replied` is published with an empty excerpt. It also documents the 409 reopen_expired error and the 200 unchanged-case behavior, which is exactly the kind of side-effect detail annotations (readOnly=false, destructive=false) cannot carry.

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?

Front-loaded and readable, but the 30-day rule and the 'open a new case instead' fallback are stated twice in near-identical wording, and the title is restated verbatim in the first line. The support-case-vs-issue guidance is valuable, but the redundancy costs it points.

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?

With no output schema and a single param, the description fully covers what an agent needs: precondition (case must be closed), time window, resulting state, emitted events, and both failure and no-op outcomes. Nothing material is left unstated.

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?

Only one parameter and schema description coverage is 100%, so the schema already defines `case_id` including its ULID pattern. The description adds no format or sourcing detail for the id beyond what the schema states, so the 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 concrete verb (reopen) and resource (closed support case) with a hard constraint (within 30 days) and scope (any member). It also names the alternative path explicitly ('open a new case'), so an agent can separate it from close_support_case and open_support_case without reading either schema.

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?

Gives explicit when/when-not: use within `reopen_until`, after 30 days you get 409 reopen_expired and should open a new case instead; a case that is not closed is a no-op 200. It further routes the agent to reply_support_case as the next step and draws a clear boundary against issues (create_issue, search_issues).

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