list_accounts

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

Annotations declare readOnlyHint=true and destructiveHint=false. Description adds important behavioral details: 'No network call. Never returns API keys or any secret material.' Also notes it's stateless (no tool changes active account). These add value beyond annotations.

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?

Description is well-structured: purpose first, then usage guidelines, then behavioral notes, then return format. Each sentence adds value. No fluff. Front-loaded with the main purpose.

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 the tool's simplicity (0 params, read-only, no network), the description is complete. It explains the return format explicitly (JSON with `accounts` array of objects). Output schema exists, so return format is further clarified.

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?

Input schema has zero parameters, so description cannot add meaning to parameters. However, with 0 parameters the baseline is 4, and description does not need to add parameter info. It appropriately omits any param discussion.

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?

First sentence clearly states the verb 'List' and the resource 'Mailchimp accounts'. It distinguishes from sibling `get_account_info` by noting that list_accounts is for discovery of account names used by other tools, while get_account_info is for live stats.

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 states when to use: 'to discover the account names accepted by the `account` argument on every other tool.' Also clarifies when not to use: for live stats use get_account_info. Explains multi-account setup and statelessness.

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