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

Annotations already flag non-read-only, non-idempotent, non-destructive. The description adds the crucial side effect that the action 'is recorded either way and matched to the card or account transaction when it appears,' which annotations alone would not reveal. It omits auth requirements and rate limits, so it is not a 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 sentences, front-loaded with the trigger and decision, and no padding. The approval-parenthetical is slightly dense but earns its place by explaining the follow-up call.

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?

It covers the decision outcomes, the recording behavior, and the approval follow-up, and the output schema handles return values. For a 10-parameter tool with zero schema descriptions, however, it never explains the key inputs (amount, agent, card, rail, kind), leaving an agent to guess their meaning.

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 carry the burden. It explains only action_id (reuse for polling approval) and references agent_action, but leaves eight parameters—agent, amount, card, run, kind, rail, payee, purpose, currency—semantically unexplained beyond their names.

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 ('check before an AI agent spends money') and enumerates the three possible answers (allow, approval, deny). It also names the sibling tool agent_action as the way to retrieve a decision, so an agent can distinguish it from passive viewing tools like agent_spend_view.

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 timing is explicit ('Call before an AI agent spends money'), and the approval path is spelled out ('call again with the same action_id, or agent_action'). It does not say when not to use it or contrast it with get_spend/limits, but the core when-to-use guidance is clear.

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