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

The annotation readOnlyHint=true already covers the safety profile, and the description adds the cost detail ('Free') and the fact that it returns account-related data. It does not add much behavioral context beyond what annotations provide, such as authentication requirements or response format details. The description is not misleading and is consistent with the read-only annotation.

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 short and front-loaded, with the core result ('Your handle, wallet, balance and usage') stated first. The 'Free' information is repeated twice, once in the opening and again as 'Price: Free,' which is slightly redundant but not harmful. Overall it is efficient and easy to parse.

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-parameter, read-only identity/balance tool, the description provides enough context: what data is returned, when to use it, and that it is free. There is no output schema, but the listed fields ('handle, wallet, balance and usage') give a reasonable expectation of the response. No critical information appears missing for an agent to invoke it 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 there is nothing for the schema or description to document. Schema coverage is trivially 100%, and the description's mention of 'wallet, balance and usage' gives the agent a sense of what data will be relevant. This fully satisfies the baseline for a parameterless 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 clearly identifies the tool as returning the caller's handle, wallet, balance, and usage, which is specific enough to understand its purpose. It lacks an explicit verb like 'retrieves' or 'returns,' but the title 'Who am I' plus the listed data makes the function clear. It does not explicitly differentiate from siblings, though its identity/account scope is distinct from tools like credit_deposit or identity_create.

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 when-to-use scenarios: 'check your balance before a run' and 'confirm your token still works.' This provides clear practical context for an agent deciding to invoke it. It does not mention alternatives or when not to use it, but for a trivial identity/balance check the use cases are sufficient.

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