Save the providers the user uses

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

With no annotations provided, the description carries the full burden and does disclose important traits: this is a full replacement of the saved wallet (implicitly destructive), only names should be stored, and card numbers/balances/personal details must never be asked for or stored. It omits auth requirements, error behavior, and what an empty array does, which keeps it below 5.

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?

Three tight sentences with no filler, front-loaded with the replace action and immediately followed by the purpose and the safety boundary. Every sentence earns its place.

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 single-parameter setter with no output schema and no annotations, the description covers what is stored, the replacement semantics, and the privacy constraints. The remaining gap is return/confirmation behavior and the empty-array edge case, which are minor.

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 description coverage is 0%, so the description must compensate. It clarifies that the array elements are provider names in the exact form shown in results and gives examples (cashback portal, gift card seller), which is meaningful. However it does not mention the 100-item cap, 80-char limit, or whether an empty array clears the wallet.

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 (replace) and resource (the saved wallet) plus exactly what is stored: provider names as they appear in results, with concrete examples. The 'replace' framing distinguishes it from the read-only wallet_get sibling without needing to open either schema.

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?

'Used to rank the user's own providers first' gives clear context for why and when the tool is invoked, which is more than a bare 'set'. It stops short of naming alternatives or stating exclusions (e.g., use wallet_get to read, or what happens on an empty list).

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