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

With no annotations, the description carries the full burden and does disclose the two facts that matter most for a mutation: the old key is invalidated (destructive side effect) and the replacement is returned only once (one-shot output the agent must persist). It omits authorization requirements, failure/idempotency behavior, and what happens if the transaction hash does not match the challenge.

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 short sentences with zero waste: action, return/effect, and the mandatory next step, ordered by importance. Nothing repeats the schema or pads the definition.

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 destructive, one-shot credential rotation with no annotations and no output schema, the description does cover the return value and the key-invalidation side effect, which is the core gap. However, with four undocumented parameters at 0% coverage and an unexplained two-value method enum, an agent still lacks enough to call it correctly without inspecting the raw schema.

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 explain the four required parameters and it explains none of them by name. The phrase 'challenge-specific zero-USDC action' loosely hints at the relationship between challengeId and the method enum (approve_zero/transfer_zero), but the agent gets no guidance on the wallet or transactionHash fields beyond their patterns.

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 resource ('Rotate a merchant API key') plus the gating condition (wallet tool has submitted and confirmed a challenge-specific zero-USDC action), which implicitly separates it from the sibling signature-completion tool. It stops short of naming the alternative sibling explicitly, so an agent must infer that this is the on-chain-transaction path rather than the signature path.

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 precondition for invocation ('after the wallet tool submits and confirms...') and an immediate follow-up obligation ('Store the new key... immediately'). It does not state when not to use it or name the sibling signature tool as the alternative branch, so the routing guidance is contextual rather than explicit.

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