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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is fully covered. The description adds only a hint of return content ('tier limits and balance'), and since there is no output schema, it stops short of describing the response shape.

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?

Seven words with zero bloat, and it is front-loaded. However it is a bare noun phrase rather than a statement of purpose, so the brevity reflects under-specification rather than disciplined conciseness.

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-required-param read tool with rich annotations but no output schema, the description should convey what is returned. It partially does ('tier limits and balance') but leaves 'passport' unexplained and gives no sense of the response fields.

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?

Schema coverage is 100% and the sole api_key parameter is fully documented in the schema, including the Authorization/env fallback. The description adds nothing about the parameter, so the baseline 3 applies.

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 phrase 'Your passport, tier limits and balance' gestures at returning the authenticated agent's identity/profile data, but 'passport' is figurative and no explicit verb+resource is stated. It does not differentiate from siblings like balance, my_credits, or get_agent.

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?

No when-to-use guidance is given, and no alternatives are named even though balance, my_credits, my_rewards, and ledger all appear adjacent in the sibling list and likely overlap. The agent must guess when this tool is the right call.

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