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

Annotations only say readOnlyHint=true and openWorldHint=false; the description goes well beyond by disclosing the required permission (checkout:create, same as create_checkout), the visibility restriction ('Only your own checkouts are visible'), refund semantics on held/needs_refund, and the meaning of a pending+cannot_pay combination. No contradiction with the read-only annotation — this is purely a status read.

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?

Information-dense with almost no filler, but it is delivered as one sprawling semicolon-chained sentence that mixes return-value semantics, next-step routing, marketing guidance for pairs_well_with, and permission notes. The status list is front-loaded, yet the run-on form makes it hard to scan and the pairs_well_with instructions are verbose relative to their importance.

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?

There is no output schema, so the description carries the full burden of explaining return values, and it does: it defines every status string, poll_after_seconds, next_call, and the pairs_well_with payload shape including price and license scope. For a one-parameter read tool, nothing an agent needs to act on the result is missing.

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 100% and the single checkout_id parameter is already documented in the schema as 'The checkout_id from create_checkout'. The description only echoes the create_checkout provenance and adds no format, length, or edge-case detail. Baseline 3 applies when the schema does the work.

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+resource ('Status of a checkout from create_checkout') and then enumerates every status value with its meaning (pending, paid, confirm, expired, failed, held, needs_refund, cannot_pay). An agent can distinguish this lookup-by-id status tool from siblings like list_orders or get_license without opening a 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?

Gives explicit routing: 'paid ... call get_download', 'next_call ... is the exact next tool call (get_download once paid; create_checkout or renew_updates with the same order after expired, failed or cannot_pay)'. It also states prohibitions ('never pay again', 'don't send the owner to it', 'never add one or start a checkout for it unless the owner asks'), which is exactly the when-not guidance most tools lack.

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