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

Goes well beyond annotations by disclosing that it spends existing credits immediately, is preparation-only, and does NOT buy credits, change settings, approve the call, or exceed the connection limit. The idempotent-retry instruction adds useful operational context consistent with idempotentHint=true.

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?

Front-loads the core action and prerequisites before the scope exclusions, with no filler. The multi-clause negative list is dense but each clause earns its place by preventing misuse.

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 an output schema and annotations present, the description needn't cover returns. It supplies the prerequisite state (owner consent), the side effect (credit spend), scope boundaries, and retry behavior, leaving nothing an agent needs to call it correctly.

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 coverage is 100%, so the baseline is 3, but the description adds meaning: ownerConfirmation is the owner's own accepted words and the remaining arguments come from the 'next' block in a reply. This sourcing detail is not obvious from the schema alone.

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+resource: accepting the shown price and spending the owner's credits. It explicitly signals what it is not ('doesn't approve the call'), which separates it from the sibling approve_call without needing the 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?

Gives clear invocation context ('after the owner says yes in this conversation') and retry guidance ('Retry a lost reply with identical arguments'). It does not name a competing alternative ('use X instead of Y'), so it stops short of full 5-level routing.

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