list_accounts

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

There are no annotations, so the description carries the full burden of behavioral disclosure. It adds a meaningful and reassuring behavioral guarantee: 'never includes credentials', which helps an agent understand safety and privacy boundaries. It does not mention other behavioral aspects, but for a simple read-only listing operation this is a strong and sufficient disclosure.

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, focused sentence that front-loads the tool's purpose and adds one critical safety note. Every word earns its place; there is no redundancy or unnecessary detail.

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 zero-parameter listing tool with an output schema already defined, the description is complete. It tells the agent what will be listed and explicitly rules out credential exposure. Sibling tools for emails, mailboxes, and labels are clearly distinct, and no additional preconditions or return-format explanations are necessary given the output schema.

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 has zero parameters, so there is no parameter semantics to explain; the baseline of 4 applies. The description's credential note refers to output behavior rather than parameters, which is appropriate and does not leave any input ambiguity.

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: 'List configured ProtonMail accounts'. The qualifier 'never includes credentials' proactively distinguishes this from potential account-related tools and adds important scope clarity. It clearly separates this tool from sibling tools focused on mailboxes, emails, labels, and actions.

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 implies when to use the tool: to list configured accounts. However, it provides no explicit guidance about when not to use it or which sibling tool might be an alternative for account-related information, such as bridge_status. The usage context is understandable but left to inference.

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