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

No annotations are provided, so the description carries the full behavioral burden, yet it discloses almost nothing operational: no return format, no indication that the result is scoped to the authenticated caller, and no auth context beyond what the schema says. 'Passport, tier limits and balance' names topics but not behavior.

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?

It is a single short fragment with no wasted words, which is good, but the terseness crosses into under-specification for a tool with no annotations and no output schema. Sentence fragment style makes it hard to front-load meaning.

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?

With no annotations and no output schema, the description is the only place an agent could learn what this returns and under what conditions, and it doesn't. Given the conceptual overlap with many siblings, more context was warranted.

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?

With one optional parameter and 100% schema description coverage, the schema already explains the api_key fallbacks (header, env var). The description adds nothing about parameters, which is acceptable at this coverage level.

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 name 'whoami' plus 'Your passport' conveys an identity-introspection tool, and 'tier limits and balance' hints at the returned content, distinguishing it somewhat from siblings like balance and my_credits. However, it never states a verb or explicitly says it returns the calling agent's identity/profile, relying on metaphor an agent must decode.

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?

There is no statement of when to call this versus alternatives such as balance, my_credits, or get_agent, despite those siblings overlapping in subject matter. Usage is left entirely to inference from the name.

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