AI wallet balance

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds non-obvious behavior beyond that: the top-up cannot be performed by the agent, the URL must be surfaced to the user, and the agent should wait — a meaningful constraint not derivable from annotations.

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?

Two short sentences, no filler, and the top-up caveat is stated up front alongside the content summary. The telegraphic first sentence is slightly clipped but costs nothing in length.

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 output schema, the description carries the burden of explaining return values, and it does list the key fields (balance, rate, AI keys, topUpUrl). It stops short of describing structure or units, but for a zero-parameter read tool that is a minor gap.

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?

Zero parameters, so the baseline is 4 and there is nothing for the schema to document. The description uses the space productively by enumerating what comes back (balance, rate, keys, topUpUrl), which is the only parameter-adjacent semantics an agent needs here.

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 names the specific resources returned — balance, per-usage rate, and AI keys on the account — which clearly separates it from siblings like create_ai_key or request_keys. It lacks an explicit verb (it reads as a noun phrase describing return contents rather than 'retrieve the wallet'), so the action must be inferred, but the purpose 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?

The line 'Only the user can add money: give them the `topUpUrl` and wait' gives real operational guidance about the top-up handoff and implicitly frames this as a read-only inspection call. However, it never states when to call this versus create_ai_key or request_keys, so the agent must infer the boundary.

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