Link to buy credits

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

readOnlyHint=true is consistent, and rather than restating it the description explains the practical consequence: the tool never pays and never touches payment details, so settlement happens out-of-band by the user. It also tells the agent the returned domain and the post-condition to verify. Link expiry or reuse rules are not covered.

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, front-loaded with what is returned and immediately followed by the key behavioral constraint. Every sentence carries information; none is filler.

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 simple two-parameter, no-output-schema tool, it covers the return value, the responsibility split, and the follow-up verification well. The remaining gap is parameter-level guidance for choosing a bundle and the currency default.

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 carries the burden but adds only 'credit pack' as a gloss for bundle. currency is never mentioned, and nothing explains tier selection or defaulting behavior. The enums supply valid values but no meaning, leaving a real gap.

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: returns a checkout link where the user buys a credit pack. It distinguishes the tool's action (returns a link) from the user's action (buys and pays), which is valuable. It doesn't explicitly contrast with the nearby sibling list_credit_packs, keeping it just short of a 5.

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 flow guidance: hand the link to the user, then check get_balance. That names a sibling and a follow-up step. It stops short of a 5 because it never states when to choose this over list_credit_packs or what prerequisites exist for generating a link.

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