mail_accounts

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

The readOnlyHint annotation already declares this is a safe read operation. The description adds 'No secrets' which tells the agent that no sensitive data (like tokens or passwords) will be returned – a useful behavioral note. However, it doesn't disclose other potential behaviors like rate limits, authentication requirements, or output structure (though output schema exists). Given the annotation covers the safety profile, the description adds modest context, so a 3 is appropriate.

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?

Two sentences with zero waste. The primary purpose is stated first, and the 'No secrets' note is a compact addition. It is front-loaded and every word earns its place.

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 parameterless list tool with an output schema present, the description is complete. The agent knows what to call it for, and the output schema handles the return shape. No further behavioral context is needed given the simplicity and the annotation coverage.

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?

There are zero parameters, so the baseline is 4 per the rubric. The description doesn't mention parameters (there are none), so it doesn't add or subtract. The high schema coverage (100% with no params) means nothing is missing. The description is sufficient.

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 uses a specific verb 'List' with a clear resource 'this user's connected mailboxes' and adds 'provider types' to clarify the scope. It distinguishes itself from siblings like mail_send, mail_read, mail_create_draft, which handle different actions, so an agent can immediately tell this tool is for enumeration of accounts.

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 implicitly tells the agent when to use this tool: whenever the user needs to see their mailboxes or providers. It doesn't explicitly list alternatives or exclusions, but the purpose is so distinct from the sibling tools (send, read, search, etc.) that usage context is clear. A minor gap is no explicit 'use this for listing accounts' but it's strongly implied.

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