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

Adds real context beyond the annotations: 'Does not charge and does not transfer funds' clarifies that no money moves server-side despite the Stripe framing, and 'Same connector and same wallet. Not a new wallet' rules out resource creation. It does not say what happens on repeated calls (multiple concurrent sessions), which idempotentHint=false only hints at, so it falls short of a 5.

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 the key action and short overall. Some redundancy in the staccato fragments 'Same connector and same wallet. Not a new wallet.' — the second sentence restates the first — but the cost is small.

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?

Covers the action, the non-obvious side effects, the sibling routing, and the setup prerequisite URL. With no parameters and no output schema, the only missing piece would be the return value, and 'Create a ... session URL' already tells the agent it gets a URL back.

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?

The tool takes zero parameters, so there is nothing to disambiguate; baseline is 4. The description correctly implies the wallet is implicit from the caller's connection context.

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 artifact — 'Create a Stripe Checkout session URL' — scoped to 'this connected wallet'. It is unmistakably different from the sibling get_credits, which reads a balance.

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 an explicit exclusion and the alternative: 'Do not call this to read the balance; use get_credits.' It also explains the human-in-the-loop flow ('The human opens the URL and pays on Stripe'), so the agent knows this is a hand-off tool, not an autonomous payment.

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