Start a Stripe checkout for a plan; returns the hosted URL

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

Beyond the annotations (readOnlyHint=false, openWorldHint=true), the description discloses that this is a WRITE, that nothing is sent without confirm: true, and that there is no server-side dry run — material behavior for a mutating billing call. It stops short of stating side effects such as subscription creation or idempotency behavior.

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?

Two tight sentences, front-loaded with the action and return value, followed by the write-safety caveat. No filler, though the parenthetical route path is of marginal value to an agent.

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 mutating, open-world billing call with a nested body and no output schema, the description covers the return value and the confirm safety requirement. It leaves gaps on what planId accepts and what the preview response contains, which matter for correct invocation.

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 67%: confirm and idempotencyKey are already documented in the schema, and the description mainly restates the confirm semantics. The required nested field body.planId has no explanation anywhere, and the description adds no meaning about accepted plan identifiers.

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 ('Start a Stripe checkout for a plan') plus the outcome ('returns the hosted URL') and even the underlying route. It doesn't explicitly distinguish itself from billing_portal or billing_overview, so it stops 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?

The confirm gate gives a concrete execution rule and warns there is no server-side dry run, which is useful usage context. However, it offers no guidance on when to pick this over the sibling billing_overview/billing_portal tools, leaving that inference to the agent.

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