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

Beyond the readOnly/openWorld annotations, the description discloses the async delivery model (link emailed to the account address), that the call returns only a confirmation, that the export is private to the caller, and the auth requirement (Cotlet API key with app access). That is substantial behavioral context. It stops short of stating rate limits or turnaround time.

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?

Purpose is front-loaded, but the description is padded: the fact that Systeme.io emails the download link to your account address is stated twice in near-identical wording, and "The export reaches only you" re-covers the same ground. It is readable but wasteful.

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?

With no output schema, the description correctly pre-empts the return-value question by explaining the call returns only a confirmation and the file arrives by email. That covers the main ambiguity for an async export tool; only the lack of explicit sibling routing keeps it short of complete.

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 100%, so the schema already documents to/from/delimiter. The description only restates the optional date range and says nothing about the delimiter parameter or date format, so it adds no meaning beyond the structured fields. Baseline 3 applies.

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 gives a specific verb+resource ("Starts a CSV export of transactions") and clarifies it mirrors the Transactions page export. It is clear what the tool does, but it never names or contrasts the obvious sibling systeme-io_list_transactions, so an agent must infer the distinction between exporting and listing.

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?

It implies the use case via "for transactions in an optional date range" but gives no explicit when-to-use versus list_transactions or get_transaction. No exclusions or alternatives are stated, so usage must be inferred.

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