buy_credits

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively explains key behaviors: that it returns a Stripe checkout URL, requires human intervention for completion, and that credits are added automatically after payment. It doesn't mention rate limits, authentication details beyond the api_key parameter, or error conditions.

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 perfectly structured and concise. It begins with the core purpose, explains the return value and usage flow, then provides parameter semantics in a clean 'Args:' section. Every sentence earns its place with no wasted words.

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?

Given the tool's moderate complexity, no annotations, 0% schema coverage, but the presence of an output schema, the description is remarkably complete. It covers purpose, behavior, parameters, and workflow. The output schema presumably handles return value documentation, so the description appropriately focuses on the purchase process and parameter meanings.

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?

With 0% schema description coverage, the description fully compensates by providing clear semantic meaning for both parameters. It explains that 'api_key' is the user's API key and that 'tier' represents credit tiers with specific values ('50' or '250') and their corresponding prices. This adds significant value beyond the bare schema.

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 tool's purpose with specific verbs ('Get a checkout link to purchase more credits') and identifies the resource (credits). It distinguishes itself from sibling tools like 'check_usage' or 'estimate_agent_cost' by focusing on purchasing rather than monitoring or estimating.

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 description provides clear context for when to use this tool ('to purchase more credits') and specifies that the resulting URL should be given to a human operator. However, it doesn't explicitly state when NOT to use it or mention alternatives like whether credits can be obtained through other means.

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