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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds value beyond them by disclosing the ownership requirement and by scoping what a success does NOT prove (activation, number, call setup), which prevents over-reading the result. It stops short of describing latency, caching, or error behavior for an invalid session.

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?

Three tight sentences: purpose first, required inputs second, boundaries and the sibling hand-off last. Every clause carries information, and nothing is restated from the title or annotations.

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?

An output schema exists, so return values needn't be explained, and the description covers ownership, input provenance, sibling routing, and mutation boundaries. The remaining gap is input validation semantics (format/expiry of session_id), which is minor given a two-parameter read-only tool.

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 carry parameter meaning, and it only supplies provenance ('from checkout') for the two IDs. It does not explain expected formats, whether session_id is a Stripe session token, or what happens with an expired or mismatched session. Useful but partial compensation for the coverage gap.

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 names a specific verb and resource ('Read a Stripe-verified subscription checkout receipt') plus an ownership scope ('for a business you own'). It also explicitly separates itself from get_activation_status, so an agent can route between the two without opening either 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?

It states the precondition for use (business_id and session_id from checkout) and names the alternative with the deciding condition: 'Confirmed billing does not prove agent, number, or call activation; get_activation_status reports setup proof.' It also gives an explicit exclusion against create_checkout/retries ('never creates checkout or retries provisioning').

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