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

The annotations already declare read-only, idempotent, open-world, non-destructive behavior, so the safety profile is covered. The description adds useful behavioral context by saying the response includes product overviews, plan and contact usage, and chat-versus-app capabilities, though it does not describe response structure in detail.

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 definition is front-loaded with the key usage instruction and then explains what the tool returns. Every clause is relevant: trigger conditions, source of truth, product coverage, account usage, and chat/app scope.

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?

Given that there are no parameters and no output schema, the description carries the needed context well. It explains when to call the tool, what broad information it returns, and how the agent should use the result.

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?

The tool takes no parameters and the schema is empty, so there are no parameter semantics to get wrong. The baseline for a zero-parameter tool is 4, and the description does not need to compensate for missing input documentation.

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 states a specific verb and resource: it returns an overview of every Mailercloud product plus account plan and contact usage. It also distinguishes this tool from the surrounding sibling tool list by explicitly telling the agent to start here rather than infer capabilities from the tool list.

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 gives explicit triggering conditions: when the user asks what you can do, what Mailercloud offers, or how to get started. It also gives a clear execution instruction: call this tool first and answer from its overview, not from the tool list.

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