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

Annotations already establish non-read-only, idempotent, non-destructive, closed-world, so the bar is lower; the description still adds real behavioral content by disclosing that action_steps replaces the stored checklist and that every step must be passed with a done flag. That warned-about full-replacement semantics is the main gotcha not visible from annotations alone.

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?

One sentence, front-loaded with the primary action, with the id-source hint and the checklist replacement rule attached where they matter. No filler or restatement of the title.

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 5-parameter, 2-required mutation tool with no output schema and closed-world semantics, the description plus annotations plus schema cover what an agent needs to call it correctly: what changes, how to source ids, and how the list replacement behaves.

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 60%, so the schema documents site_id and user_goal itself. The description compensates on the ambiguous parts: it enumerates the four status values and spells out that action_steps is a complete list with per-item done true/false, which is the non-obvious contract for that array.

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?

Specific verb (mark/update) plus resource (one marketing idea), and it names both mutation axes: the status enum values and the action-step checklist. It also points at list_marketing_ideas as the source of ids, which separates it from the read-side sibling, though it doesn't explicitly disambiguate from other update_* tools.

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?

"and/or" implies both fields are independently optional, and the parenthetical tells the agent where to get ids, so usage is inferable. There is no explicit when-to-use/when-not statement, no prerequisite or permission note, and no guidance on whether status changes have allowed transitions.

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