setup_metered_billing

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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions the creation of a subscription and pricing, but doesn't cover important aspects like required permissions, whether this is a one-time or recurring setup, what happens if setup fails, or any rate limits. For a billing setup tool with zero annotation coverage, this leaves significant behavioral gaps.

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?

The description is extremely concise with just two sentences that directly state the tool's purpose and key details. Every word earns its place, and the information is front-loaded with no unnecessary elaboration or repetition.

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 billing setup tool with no annotations and no output schema, the description is insufficient. It doesn't explain what happens after setup, what the subscription entails, how users are notified, what the return value is, or error conditions. Given the complexity of financial operations and lack of structured data, more context is needed for the agent to use this tool effectively.

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 100%, so the schema already documents all three parameters. The description doesn't add any parameter-specific information beyond what's in the schema. The baseline of 3 is appropriate when the schema does the heavy lifting, though the description could have explained why the email is required or how the URLs are used.

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 description clearly states the specific action ('Set up pay-per-call billing') and resource ('creates a subscription'), with precise pricing details ($0.002 per API call). It distinguishes from siblings like 'add_credits' or 'purchase_access' by focusing on metered billing setup rather than other financial operations.

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?

No guidance is provided on when to use this tool versus alternatives like 'add_credits' or 'purchase_access'. The description mentions what it does but doesn't specify prerequisites, timing considerations, or when not to use it. This leaves the agent without contextual usage direction.

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