Show this key's account and limits

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description does add useful context on what is returned and implies spending thresholds exist ('without asking'), which matters behaviorally. It does not cover failure modes (e.g., what happens with an invalid or expired key) or the format of the response, so it goes beyond annotations but without much depth.

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?

One sentence for usage plus one for returns, with the usage trigger front-loaded. The returns clause is a long run-on list, though each item is meaningful and not wasted.

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?

Because there is no output schema, the description carries the burden of describing the return value, and it enumerates the returned fields including the portfolios, which are nested in practice. It omits error conditions and whether the returned limit figures are currency amounts or call counts, a small remaining gap for a zero-parameter tool.

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 no parameters and the description correctly presents it as argument-free, so there is no parameter semantics to explain. Baseline 4 applies for a zero-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?

States a specific verb and enumerates the exact contents returned: account, key name, spend limits for the day and month, wallet balance, free calls left, and portfolios with ids. No sibling in the tool list overlaps with this introspection role, so the scope is unambiguous.

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?

Gives a clear trigger condition: use it when the person asks what the key or connection can spend or how much is left, and front-loads the context 'before spending on the person's behalf'. It does not name alternative tools or exclusions, but no sibling plausibly competes with this one.

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