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

Goes well beyond annotations: the return shape (a hosted Stripe URL), the guarantee that a saved card is never silently charged, that the human confirms on Stripe, that the org comes from the key and not the body, and the required billing:write scope. The non-destructive/one-off nature aligns with destructiveHint=false and is reinforced rather than merely repeated.

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-loaded with purpose and return value, then constraints, then when-to-use. Dense and mostly waste-free, though the multiple mid-sentence clauses and emphatic caps make it slightly heavier than necessary.

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 present the description needn't detail returns, yet it summarizes { url } anyway plus auth scope, org resolution and eligibility criteria. Complete enough that an agent can select and invoke it correctly on the first try; the only loose end is the unmentioned `interval` field, which is a schema inconsistency more than a description omission.

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 compensate: it enumerates the three plan values and explains that the org is never passed in the body. However it is silent on the schema's `interval` field, which it arguably contradicts by declaring 'no subscription tiers' — a real gap in parameter coverage.

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 up front: 'Top up the CURRENT org's credit wallet.' An agent can tell this apart from billing siblings like list_plans (discovery) and get_account (balance check) without opening any 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?

Explicit when-to-use ('Only send a user here when get_account shows the relevant balance at or near zero') and explicit routing to the discovery alternative ('Discover the packs with list_plans'). The when-not condition is inferable from that same sentence.

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