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

Strong for a stub: it discloses that no rate source exists, that wallet charges are USD, that no invented rate will be returned, and that 'nothing is read or changed'. This adds real behavioral context beyond the readOnlyHint/destructiveHint annotations. Minor tension between 'nothing is read' and readOnlyHint=true, but not a contradiction since readOnlyHint concerns mutation.

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?

Short and front-loaded, but the four sentences largely restate one idea — no rate source, unsupported, no invented rate, nothing changes. The redundancy is tolerable but doesn't earn every sentence.

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 disabled stub, the description is arguably sufficient to prevent a bad call, and no output schema is needed. But with seven undocumented parameters and no pointer to a working alternative, an agent is left without a next step.

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?

Seven parameters at 0% schema description coverage, and the description explains none of them — not 'from'/'to' currency codes, not 'amount' bounds, not 'confirm' or 'acknowledgedAmountUsd'. The description must compensate here and does not at all.

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 and title say 'Convert currency', but the description never states what the tool does or would do — it only declares that it cannot do it ('not yet supported', 'no foreign-exchange rate source is configured'). An agent learns the tool is a non-functional stub, which is useful, but gains no positive statement of purpose or scope.

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?

Usage is implied rather than stated: 'not yet supported' signals do-not-call. However, it names no alternative — sibling tools like get_supported_currencies or get_wallet_balance would be the natural substitutes, and the description never routes the agent there.

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