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

Annotations already declare destructiveHint=true and openWorldHint=true, so the risk profile is covered structurally. The description adds genuinely new behavioral context — that this is the terminal, irreversible-feeling step of a gated workflow and that a body built without the discovery calls will be wrong. It stops short of saying what the action mutates or how failures surface, but given the annotation coverage this is solid.

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 with 'REQUIRED: Complete these steps first', and the numbered steps are easy to follow. The closing 'Always call step 2 to see the exact body structure before executing' partially repeats step 2's own wording, a small redundancy that still earns its place as an emphasis on the most failure-prone omission.

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?

An output schema exists so return values need no explanation, and annotations carry the destructive/open-world safety profile. For a tool whose entire input is a dynamically constructed body, the workflow pointer to actions_details is the critical missing piece and it is present. Only the absence of any error/partial-failure guidance keeps it from a 5.

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 0% and the sole parameter is a free-form object with additionalProperties=true, so the schema alone tells an agent nothing about what to put in body. The description compensates by directing the agent to actions_details for the exact body structure and insisting it follow the schema exactly. That is the right semantic guidance for an opaque body, though it doesn't describe any body keys itself.

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+resource ('Execute Klaviyo action') and positions itself as the final step of a three-step workflow, which separates it from query_contexts (preparation) and query_data. The term 'action' remains generic — the description never says what kinds of actions exist — but the workflow framing makes the tool's role unambiguous.

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?

Explicitly enumerates the prerequisites: call query_contexts with request='accounts' for workspace_id, brand_id and available_actions, then request='actions_details' for the specific action body structure. It also names the alternative tool (query_contexts) and states a hard rule ('Always call step 2'), leaving nothing to inference.

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