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

Beyond the annotations, the description discloses two non-obvious behaviors: steps are replaced wholesale rather than merged, and step edits on a running campaign may require operator approval. It also states the required manage_campaigns scope, which annotations do not cover. Minor tension worth noting: replacing steps overwrites prior step definitions while destructiveHint=false; the description does not clarify whether omitted fields are preserved (partial update) or reset.

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?

Three compact sentences with zero filler; the primary capability leads, and the two operational constraints (approval, scope) follow. Nothing is repeated from the title or 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 15-parameter mutation tool with nested objects and no output schema, the description covers approvals and scoping but leaves out patch semantics (are omitted fields kept?), what the response returns, and any hint about the untyped parameters like window and stop_on. It is adequate but leaves real gaps for a high-complexity tool.

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 a middling 60% — the steps parameter has a very rich schema description, but window, stop_on, send_days, skip_dates, and track_opens are undocumented anywhere. The description adds no parameter-level meaning at all, so the agent must fall back entirely on the schema for a 15-parameter tool.

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 ('Change a campaign's settings and/or replace its ordered steps'), which cleanly separates it from create_campaign, get_campaign, and the pause/resume pair. The 'replace' wording additionally distinguishes a full overwrite from an incremental patch. It never names a sibling tool explicitly, so it stops just short of 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?

The approval clause gives useful situational context for editing a running campaign, but there is no explicit when-to-use vs when-not guidance against the 28 siblings — nothing tells the agent to use pause_campaign or launch_campaign instead of editing settings directly, nor when an update should be skipped. Usage is implied by the resource only.

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