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

Annotations already grant readOnlyHint=true, so the safety profile is covered; the description adds the valuable non-obvious trait that actions_details is a mandatory precondition and that specific data (request body, required identifiers, fields, time ranges, notes) is only obtainable there. It does not discuss error behavior or how to recover from an invalid action id, but with an output schema present the return-shape burden is lifted.

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?

The step-numbered layout is front-loaded and scannable, with each line corresponding to a request mode. There is mild redundancy in restating that available_actions is already included in the accounts response, but that repetition serves a routing purpose rather than padding.

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 five-parameter, read-only, multi-mode metadata tool with a full output schema, the description covers the workflow, the mandatory ordering, and the optional branches well enough to call it correctly. The unaddressed `platform` parameter and the absence of any guidance on invalid or missing workspace/brand ids are the remaining shortfalls.

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%, so the description has to carry all parameter meaning, and it largely does: it enumerates all four `request` values with their purpose, explains `actions` as an array of identifiers sourced from available_actions, and notes brand_id + workspace_id usage for the brands mode. The `platform` parameter is never mentioned anywhere, which is the one real gap.

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?

The description establishes that this is a setup/metadata-discovery tool for Klaviyo queries rather than a data-returning query tool, and the four request modes (accounts, brands, available_actions, actions_details) define its actual surface. It is specific about resources even though the framing sentence ('Helper for planning...') is a bit soft. It does not explicitly name which sibling it feeds into, which keeps it from a 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?

Provides an explicit ordered workflow (Step 1 accounts → Step 2 actions_details) and marks actions_details as REQUIRED before querying, which routes the agent away from premature query calls. It also flags two optional calls and even explains that available_actions is redundant with data already in the accounts response, which is a genuine when-not-to-use signal.

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