list_available_accounts

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

The description adds meaningful behavioral context beyond the annotations: accounts are 'stable' and 'non-secret', and the tool should never trigger credential requests. It also covers the empty-result behavior, which is important for agent decision-making. This significantly exceeds what readOnlyHint and idempotentHint already convey.

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 three concise sentences with no filler. The first sentence states the core purpose, the second gives usage rules, and the third covers fallback behavior. Every sentence contributes distinct value and the structure is front-loaded and easy to scan.

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 simple zero-parameter tool with an output schema and strong annotations, this description is complete. It covers the tool's purpose, how to interpret its records, how to respond to an empty result, and what not to do. Nothing essential is missing for an agent to select and invoke the tool correctly.

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 zero parameters, so there is no parameter semantics to document in the description. The schema is trivially complete at 100% coverage. The description appropriately focuses on output interpretation instead of parameters, matching the baseline for a no-parameter tool.

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 accounts'. It further characterizes them as 'stable non-secret capability records', which clarifies both the object and the nature of the returned data. This is clearly distinct from all sibling tools, which focus on recipients, senders, emails, or mailboxes.

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 gives explicit operational guidance: use can_receive=true accounts for mail reads and can_send=true accounts for send_email and forward_email. It also provides a clear fallback instruction for empty results and explicitly forbids asking for credentials in chat. This is strong, actionable context for an agent.

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