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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=false, so the safety profile is covered by structured data. The description adds no behavioral context of its own: it never explains why an 'update' carries a destructive hint, nor the critical semantics of the all-nullable nested settings (does omitting or nulling a field leave it unchanged or clear it?).

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 sentences, zero filler, with the scope statement front-loaded and the sibling routing placed immediately after. Nothing is repeated from the title or the schema.

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 mutation tool with a nested 9-field payload, a destructive hint, and no output schema, the description is too thin. The absence of partial-update/null semantics is a consequential omission an agent needs before calling it, and the destructive flag is left unexplained.

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 0% across a 9-field nested object, so the description must compensate. It does provide a useful grouping — name, writing, follow-up, tracking — that orients an agent across most fields, but it omits exclude_html_format and include_recent_episode_ref entirely and says nothing about the anyOf-null pattern that governs every property.

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 (update) plus resource (campaign) with an enumeration of the setting categories being changed: name, writing, follow-up, tracking. It also disambiguates from the sibling schedule_campaign. It stops short of 5 because 'writing' is a vague grouping that doesn't map cleanly to the actual fields (email_length, matching_blurb, custom_instruction) and the required campaign_id target is never named.

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?

'Scheduling uses schedule_campaign' is a genuine routing hint that names an alternative and the condition that selects it. However, that is the only when/when-not guidance; nothing says whether this is a partial or full replacement, nor how it relates to get_campaign, set_campaign_mode, or disable_campaign_schedule, leaving most sibling selection to inference.

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