mailchimp_reports

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

With no annotations, the description carries the full burden and largely succeeds. It details what each action returns (e.g., 'opens (which members opened, and how often)', 'domain_performance (deliverability by recipient domain)') and flags parameter dependencies ('needs link_id', 'needs subscriber_hash'). It doesn't mention rate limits or read-only behavior, but the read-only nature is implied by its analytics purpose.

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 description is a single, dense sentence that front-loads the purpose and then enumerates all actions in a list-like structure. There is no fluff; every clause adds value. However, it is quite long and could be more readable with bullet points, so it doesn't earn a 5.

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 tool with 6 parameters, no output schema, and no annotations, the description thoroughly covers the behavior of every action and their return contents. It also notes dependencies like 'needs link_id' and 'needs subscriber_hash'. While it could mention that campaign_id is needed for most actions, the overall coverage is strong and effectively compensates for missing structured metadata.

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 baseline is 3. The description adds meaningful semantics by explaining each action enum value in detail and noting which extra parameters each action requires (e.g., 'link_id from action=clicks'), which the schema alone doesn't convey. This significantly aids correct invocation.

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 opens with 'Campaign performance analytics' followed by a specific list of metrics (opens, clicks, unsubscribes, etc.), clearly identifying the tool as a reporting tool for campaign data. This distinguishes it from siblings like mailchimp_campaigns, which focus on campaign management, and makes the tool's main function 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?

The description provides clear usage instructions by listing the 'action' options and what each does, guiding the user on which action to set for different reporting needs. It doesn't explicitly compare with alternatives, but since no sibling covers reporting, the niche is clear. The implied usage is strong due to the exhaustive action list.

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