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

Annotation contradiction: The description says 'Create a real Stripe Checkout session', implying a state-changing write operation, but the annotations declare readOnlyHint=true. This is a serious inconsistency, making the tool's behavior misleading. The description does not add any additional context about side effects, payment authorizations, or idempotency beyond the contradictory annotation.

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 two concise sentences, front-loaded with the core action and outcome. Every word earns its place; no fluff or repetition. This is an example of efficient, high-signal writing.

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?

The description covers the primary purpose and return value, but with 13 parameters and no required fields, more context is needed about the typical flow (e.g., prerequisite of obtaining a quote_id, relationship to claim_agent_checkout_key). The output schema exists, so return details are not required, but the description is minimal and does not fully guide an agent on how to invoke the tool correctly in a broader workflow.

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 input schema provides descriptions for 92% of parameters, including details like quote_id from get_agent_billing_quote and mandate_id for scoped production. The description adds no extra parameter-level meaning beyond the schema. Baseline of 3 is appropriate given high schema 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?

The description clearly states the tool's action: creating a real Stripe Checkout session for buying Toofi internal credits. It includes the resource (Stripe Checkout session) and the specific outcome (returns a claim token for later key retrieval). This distinguishes it from sibling tools like claim_agent_checkout_key and get_agent_billing_quote.

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 implies a sequence (get quote -> create checkout -> claim key) but doesn't explicitly state when to use this tool vs alternatives. No exclusions or alternative tool names are mentioned. The purpose is clear, but the 'when to use' context is only inferred, not stated.

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