Who am I

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

Beyond the readOnlyHint annotation, the description discloses the specific data returned (account, plan, scopes, live/test mode) and adds a cost-related trait ('Free'). This provides meaningful context about behavior and output, exceeding minimal annotation coverage.

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 one concise sentence plus 'Free.'—no fluff. The core action and output are front-loaded, making it highly scannable and efficient.

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 (no params, no output schema, readOnly annotation), the description fully explains what the tool does and what it returns. It lists all key output fields and the cost aspect, making it complete for an agent to invoke 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 has zero parameters, so the baseline is 4. There is no parameter information to add, and the description appropriately focuses on the tool's output rather than any input semantics.

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 clearly states the tool's function: 'Show the account, plan, scopes, and live/test mode of the configured API key.' It uses a specific verb ('Show') and resource, and it distinguishes itself from sibling tools, none of which focus on identity/configuration.

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 usage as a diagnostic tool for checking API key configuration, and the 'Free' note hints at no cost. However, it does not explicitly state when to use this tool versus alternatives or provide exclusions. For a simple zero-parameter tool, the context is clear but not explicitly guided.

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